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Hmm, weird. I ran whole TA Italia series without a singel issue on remaped stock ecu. Power still there or went in to safe mode?
Power still there, car ran great, but I was unable to change driving modes (Stuck in "N" on the DNA selector).
 

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....or you just lost another percentage of your hearing.:D:):unsure::oops::cry:
That’s my concern with the downpipe and 200CEL cat; unless muffled it’s just too loud for my already damaged hearing. A bloody nuisance.
This version does have a muffler. I agree, without would only be suitable for the track.

I wondered if I just got used to it as well, but I think as it goes through a heat cycle or two, and gets some carbon deposited, some of the volume is dampened.

It's not a screaming straight pipe V12 loud. Just about right, I'd say!

;)
 

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I've installed GMS downpipe and CAT.
Muffler is Akropovic and custom midpipe was made locally.
Like Rudi says - the low end shove has disappeared. The power moved to the mid and up RPM.
I'm totally OK with this but now it's out of sync with the gearbox auto shifting - even in Dynamic mode the RPMs that the gearbox keeps are too low to have power immediately available on tap.
The solution - control shifts manually.
Sound is louder - it's still not Ferrari and not even flat 6 Porsche - but OK.
The top end power is addictive - finally the engine revs to the top without feeling choked and power keeps growing all the way to the redline. This one aspect was really bothering me before - but now it's solved.
 

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@4Canada
Thanks, I feared that this might happen with OEM ECU, as Rudi said, OEM cat is efficient with regards to emissions. I hope its another issue, please keep us updated.
 

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@Croc
Had not anticipated that low end would suffer much. Maybe Alfa have a trick up their sleeve to increase low RPM gas speed into turbine, or something else...? Or maybe its the cooperation between cam overlap and exhaust that is giving this result, that a re- tune of this might get us the low end back. Not a task for me, thats for sure.
 

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My local exhaust fabricator immediately said to me that going up to 3" will cause torque decrease even on turbo engine.
 

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Discussion Starter #268
We all need GMS tunes and we are not far off. 😁 I just really want to make sure that the tune is capable of delivering good numbers, utilizing all the benefits of the new exhaust and yet being able to cope with different fuel quality and ambient temps around the globe. My car and another test bunny in our country is currently running it and so far so good. It's just that nit picking, how far should you go to keep it safe. Dynoes coming soon...
 

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@4Canada
Thanks, I feared that this might happen with OEM ECU, as Rudi said, OEM cat is efficient with regards to emissions. I hope its another issue, please keep us updated.
I will, for sure.

At the moment, I am running on the assumption that my error light is an install problem, or perhaps a faulty sensor. My hope is that after a heat cycle from an hour's driving, a clamp just needed further tightening.

As I said, the dash light only came on shortly into my second drive, after the engine had sat and cooled from an hour-long shake down without problems eariler in the day.

I do not know enough about the system - there were three identical stored codes. Maybe the car only throws the dash light after three, or perhaps they all occurred on the second drive (I continued on for 20 minutes to get home after the light appeared).

My plan is to check for anything looking amiss this weekend, then clear the codes and go for a drive with my scanner at hand. I'll stop a few times and see if there are codes without a dash light. If there are, I may try to swap back to the stock O2 sensors (I had supplied new for this exhaust) to see if that makes any difference. My time, however, is limited so we'll see how far I get with this. Otherwise, it may need to go back to the dealer to see if they can find anything wrong.

Rudi ran his car for at least a while on the stock ECU without issue. But we know that the EU and NAFTA versions are somewhat different, and CARB compliance might mean more stringent monitoring of the catalyst. All just guesswork for the time being. Doing a little research on this as well.
 

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Discussion Starter #271 (Edited)
I think it all depends on the tune. There is no way that tuned engine stays within the same emissions regardless of the exhaust setup. It could be that stock ecu for NA has lower tolerances for emissions variables than EU cars, but any aftermarket tune works on the same principle...if there truly are different check engine lights built in for different markets, then all the aftermarket tunes bypass them. I'll have our tune available soon in case yours requires a tune.

Regarding the low end torque. I doubt there is any loss on tuned car when fueling is right, as backpressure has absolutely no benefits or helping low end torque or has any other positive effects. More precisely. The more the exhaust gases, higher the velocity of the gasses, lesser the backpressure and smaller the turbo, the sooner the turbo spins, which is dictating the torque curve. By adjusting valve overlapping VVT spool time and torque curve can be greatly affected. An undersized exhaust will indeed help with the spool time and low end torque as the exhaust gas velocity is higher, but you will pay the price of loss of mid and high range rpm performance, as the backpressure will be chocking the turbo, causing heatsoak, and forcing the turbo to work extra hard. The 4C power curve falls down far too soon for true sporty drive, but it is emission and fuel efficient, optimal actually. Stock ecu maps are however not optimal in terms of performance as they utilize a lot of overlapping through all the rpm range to act as an internal EGR and help with the emissions. The most noticeable in the mid range (cruising speed), that's why we have so much drone as well. They are also messing up your valves and valve ports on DFI engines for the sake of emission control.

I ran Alfaworks race ecu for some time and car felt different right from the start. There was absolutely no drone as the midrange rpm had much less overlapping than stock ecu as the emissions were not priority. It sounded much quieter because of that as well, the cold start noise was gone as yet again there was no need for heavily advanced timing to heat up the engine to working temp ASAP. Alfaworks did a good job on the tune but the dynoes and measurements showed clearly that stock exhaust is nowhere capable and designed to push over 1.5bar or 240hp steadily which is exactly where stock ecu is. Even basic online calculator tells you that stock 4C exhaust piping is the smallest recommended for given application - of course, without taking into consideration the extra low flow stock 4C cat. Stock system ecu map and stock exhaust system is optimal for effective emission control. Anything beyond, there is too much heatsoak and power instability. So why tune the stock engine if the exhaust is the bottleneck? Because it's cheap mostly. The tunes are from 400€ onward and you gain 50hp. Sounds nice, doesn't? Well, the thing is, that whatever tune you choose, whatever price you pay, you'll get the same result in the end. Unstable dyno queen car. Not a track tune. So if you want to do it right, then here is what I recommend:

1. Free flow exhaust (3" is a must for 300hp - 450hp applications with cats. Stock system is the main bottleneck)
2. Intercooler (more flow, more cooling, more heatsoak resistant)
2. Headwork porting (more flow, less backpressure, higher exhaust velocity, less carbon deposits, a lot of improvement can be done)
3. Camshafts (more agressive profiles, for better high rpm performance, required to move power curve in higher rpm)
4. Turbo (if you did the steps above, then this is currently the bottleneck)
5. Forged internals (the weak part at this point)

At any of this stage you can apply the tune which optimally, should be specifically tuned for your build. Best price / performance gain will be a tune on stock system as you will gain the most HP over stock for the least possible investment, but that's not a performance build. I know we have different ideas and the "how far you're willing to go" factor, but if perfection is the one that you are looking for and you should in the world of motorsport, than you're on the right way by following upper steps and I salute you! Say no to shortcuts. (y)
 

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I will, for sure.

At the moment, I am running on the assumption that my error light is an install problem, or perhaps a faulty sensor. My hope is that after a heat cycle from an hour's driving, a clamp just needed further tightening.

As I said, the dash light only came on shortly into my second drive, after the engine had sat and cooled from an hour-long shake down without problems eariler in the day.

I do not know enough about the system - there were three identical stored codes. Maybe the car only throws the dash light after three, or perhaps they all occurred on the second drive (I continued on for 20 minutes to get home after the light appeared).

My plan is to check for anything looking amiss this weekend, then clear the codes and go for a drive with my scanner at hand. I'll stop a few times and see if there are codes without a dash light. If there are, I may try to swap back to the stock O2 sensors (I had supplied new for this exhaust) to see if that makes any difference. My time, however, is limited so we'll see how far I get with this. Otherwise, it may need to go back to the dealer to see if they can find anything wrong.

Rudi ran his car for at least a while on the stock ECU without issue. But we know that the EU and NAFTA versions are somewhat different, and CARB compliance might mean more stringent monitoring of the catalyst. All just guesswork for the time being. Doing a little research on this as well.
A tuned ECU will most likely be more tolerant, as Rudi say, and might even neglect cat performance completely. All bets are off really, depends on what the tuner found to be sensible that day.

I have masked cat error in my cracked OEM RX8 ECU, makes the government periodical vehicle control a lot easier, since cat is removed, and emissions status can be fetched via OBD port. If they put a sniffer at end of exhaust, HC emissions would be worse than very bad😅
 

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Hi,

I am also a happy GMS3" customer (full set) ;-)
I still run OEM ECU, and I have not tracked the car yet due to the lock-down.
I still need to install my AW RACE ECU

The car now does a decent noise (my wife compared it to a lawnmower before) ... and indeed very loud ! Probably too loud for open roads and comfort/health above a certain age ;)
Looking fwd to check the difference with the AW ECU !

The central exhaust & mesh are super erotic 😍

I haven't been able to notice the torque issue at low rpm on the road, and haven't suffered from any CEL.

The disappointment was that we had to remove the swaybar. Rudi explained his standpoint already ... but it is "surprising" ;-) Any news on the GMS swaybar by the way ?

Have a good Sunday !
 

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Hi,

I am also a happy GMS3" customer (full set) ;-)
I still run OEM ECU, and I have not tracked the car yet due to the lock-down.
I still need to install my AW RACE ECU

The car now does a decent noise (my wife compared it to a lawnmower before) ... and indeed very loud ! Probably too loud for open roads and comfort/health above a certain age ;)
Looking fwd to check the difference with the AW ECU !

The central exhaust & mesh are super erotic 😍

I haven't been able to notice the torque issue at low rpm on the road, and haven't suffered from any CEL.

The disappointment was that we had to remove the swaybar. Rudi explained his standpoint already ... but it is "surprising" ;-) Any news on the GMS swaybar by the way ?

Have a good Sunday !
Wife compared it to a lawnmower???? You probably got the muffled exhaust version o_O
Did get tinnitus from this car 🎺 :cautious:
 

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...
Did get tinnitus from this car 🎺 :cautious:
I can answer from my perspective. I have tinnitus (too many years as a kid in small airplanes without any hearing protection - because you didn’t in those days). It really wasn’t made any worse by the GMS exhaust. Not having the race drone helps, too. That said, it is loud. But lower pitch. Resonated, high-flow car version here.
 

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ARB's are in the works. We still need a bit more time, but we are advancing steadily. (y)
Appreciate that you are taking the time to get these right. That extra couple of bends on each side means more rigidity required, which must be a challenge without adding too much weight.
 

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Discussion Starter #279
I've written about ARB's a lot. The main challenge is to actually make them work. Leverages are very long, the travel path is very short, only a few cm when the suspension travels, so that's why there is no major difference in terms of body roll whether you run stock ARB's or not. What stock ARBs do is mostly suspension bind and it is bad. GMS ARBs will bind the suspension too but at least they will prevent body roll. So we need stiffer torsional ARBs with the least possible weight. We have the solution on a way. Still I suggest ARBs only as an fine tuning element. First tune your spring rates, otherwise the suspension binding will increase, weight will increase, inner wheel spin will increase, nose dive and squat will remain unaffected, only body roll will decrease. ARBs should primarly be used for fine tuning understeer/oversteer balance, not for masking other suspension problems. Don't look for shortcuts, there are none if you want to do it right. 🏁
 
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