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Discussion Starter #22
Nice write-up and excellent pictures. Thanks.

I haven't even looked at my Cat, but, I suspect it was mounted to the engine before the engine was installed. Without removing the engine (or at least moving over a bit), you've done the "impossible" job.
I appreciate it. Ive heard it was the impossible job, and it has earned that title. Its definitely got a deeper tone to it and the pops and bangs now are almost uncontrollable at times. It does have a more raspy tone to it now which sucks, but thats to be expected. It was well worth it. Hope to get video at the Tail of the Dragon this weekend.
 

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CAT delete cars I have noticed really stink. How is yours? I would worry that that smell would get police attention. I know that in one US state or other country (can't remember which) it was reported here that the police are going after loud exhausts AND ticketing CATless cars with big emission fines. Hopefully you are OK.
 

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Discussion Starter #24
CAT delete cars I have noticed really stink. How is yours? I would worry that that smell would get police attention. I know that in one US state or other country (can't remember which) it was reported here that the police are going after loud exhausts AND ticketing CATless cars with big emission fines. Hopefully you are OK.
The whole reason for the cat is to filter out as much pollution out as possible. With that gone, its gonna stink. If you're driving, its not an issue. But if you're sitting in traffic or at a red light for very long with the windows down, you're gonna smell it pretty quickly. Its not pleasant, but worth it in my opinion. With the cat gone, you're likely to gain a few HP simply because there isn't air restriction either.

It is illegal to take it off, but then again, the trouble is worth it in my opinion....at least for now it is.
 

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I appreciate it. Ive heard it was the impossible job, and it has earned that title. Its definitely got a deeper tone to it and the pops and bangs now are almost uncontrollable at times. It does have a more raspy tone to it now which sucks, but thats to be expected. It was well worth it. Hope to get video at the Tail of the Dragon this weekend.
You've almost twisted my arm to remove the Cat just for the ear-candy. But sadly, here in California we have to pass a smog inspection every two years. To much work to swap out the cat...
 

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CAT delete cars I have noticed really stink. How is yours? I would worry that that smell would get police attention. I know that in one US state or other country (can't remember which) it was reported here that the police are going after loud exhausts AND ticketing CATless cars with big emission fines. Hopefully you are OK.
The whole reason for the cat is to filter out as much pollution out as possible. With that gone, its gonna stink. If you're driving, its not an issue. But if you're sitting in traffic or at a red light for very long with the windows down, you're gonna smell it pretty quickly. Its not pleasant, but worth it in my opinion. With the cat gone, you're likely to gain a few HP simply because there isn't air restriction either.

It is illegal to take it off, but then again, the trouble is worth it in my opinion....at least for now it is.
Right. The catalytic converter is simply an after-burner the makes sure all the gasses are fully spent. So, yes, the tail-pipe will have a different aroma to it.

The cat absorbs a lot of sound as well which is why we can get away with no muffler. Mine came from the factory without a muffler as did my Fiat 500 Abarth.

As an after thought here, how does you 4C run now that the Cat is missing? Did you have the ECU flashed to adjust the tune?
 
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Discussion Starter #27
Right. The catalytic converter is simply an after-burner the makes sure all the gasses are fully spent. So, yes, the tail-pipe will have a different aroma to it.

The cat absorbs a lot of sound as well which is why we can get away with no muffler. Mine came from the factory without a muffler as did my Fiat 500 Abarth.

As an after thought here, how does you 4C run now that the Cat is missing? Did you have the ECU flashed to adjust the tune?
Yes sir. Phases 2 tune, CEL delete with pops and bangs. Haven't been able to find a V2 intake in stock anywhere unfortunately.
 

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I’m wanting to do the GMS exhaust as my winter project, but the horror stories, and almost $4k, are making me question whether it’s worth it. I want to improve the sound from my race exhaust, but more so I am looking for an increase in the top end performance for track days. I currently have the V2 intake and a stage 2 tune. Has anyone realized noticeable gains?
 

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I’m wanting to do the GMS exhaust as my winter project, but the horror stories, and almost $4k, are making me question whether it’s worth it. I want to improve the sound from my race exhaust, but more so I am looking for an increase in the top end performance for track days. I currently have the V2 intake and a stage 2 tune. Has anyone realized noticeable gains?
The GMS exhaust is a good choice if your goals are top end gains and heat rejection. Noise is always subjective. I like it, others may not. Definitely louder than the race exhaust. And deeper.

What I have found, having a track season with it under my belt, is that the engine bay stays notably cooler. When I'd pit before, and lift the boot lid (whatever you want to call the back of the coupe), the blast of heat escaping would be intense. With the 3" GMS (resonated, 200 cell catalyst, heat wrapped), it is warm but nowhere near the same level. You have to lean in to within a foot or closer to the engine to feel the same amount of heat. That's got to help with heat soak, and be easier on many components.

There is (not sure why, but confirmed by Rudi and others) a loss in bottom end torque. But even on my relatively slow race track (average speed is around 65MPH with two or three straights 100-110) the top end gains outweigh the low RPM grunt. At low end, it becomes even more of a momentum car, but it surprises you how it keeps pulling at the top better now. Your tune might compensate for the lost torque somewhat (compared to stock, probably not compared to the Stage 2 with the race exhaust).

The install is dead simple except for that one fastener holding the cat/dowpipe to the turbocharger. If Alfa had put the clamp facing the other way, it would hardly be a challenge.
 

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Perfect! Thank you for that. Did you end up doing an ecu tune? If so what stage? I’m thinking with the heat wrap that I could do a stage 3 and not need to do a new intercooler? Also, I saw that you had to remove your sway bar for the exhaust. Has that been a good or bad thing for handling? Assuming you still have the stock suspension.
 

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Perfect! Thank you for that. Did you end up doing an ecu tune? If so what stage? I’m thinking with the heat wrap that I could do a stage 3 and not need to do a new intercooler? Also, I saw that you had to remove your sway bar for the exhaust. Has that been a good or bad thing for handling? Assuming you still have the stock suspension.
Sorry - did not see this before (that's bad for a moderator!)

I had an EC Stage 1 for my other car, so I sent it in to have refreshed to use on this car, and got them to ignore the Emissions Code error (or whatever they do to it, as without that the car may default to locking you into Normal drive mode due to the higher flow cat - this happened to me but not with someone else here). I kept it at Stage 1, as i wanted to be conservative on wear to the transmission, etc. Still improving my driving to get faster - don't need the car to cover up my mistakes!

Swaybar delete is less of an issue than I expected. It is required for Rudi's current exhaust setup, although he has promised a re-design which would allow it to be re-attached.
I have the base suspension on this car, and it rolls quite a bit at > 1g. I'd say more than before. It is possible that i can now be on throttle a bit sooner without wheel spin, but I'm not good enough to really be able to go about comparing that to my previous times / experience. Especially when it was 6 months between my last track day with the swaybar and first without it. I will probably upgrade suspension in a year or so, and would have deleted the bar by that point anyhow. I cannot say that I miss it as much as I was expecting. I do get a lot of understeer on one or two corners where a stock 4C gets oversteer (different driver, different tires, so how much is swaybar I don't know). I've simply adjusted my driving style to compensate, but in order to get faster I think that the swaybar or a better shock setup may be required. Note that this is for my usual, local track. Different tracks and driving styles may result in completely different results. The car is certainly no less fun and no less controllable without the rear swaybar.
 
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