jaffi

Hey guys, I just got my Stillen exhaust today. I know you guys don't like stillen that much, but it looks close to stock (as far as aftermarket stuff goes) and it is pretty quiet compared to a lot of after market catbacks. Now, the reason I wanted a quiet exhaust is because I am going to be putting test pipes in. A loud exhaust with test pipes is asking for a hefty fine. What do you guys think of this. I am hoping that I will get a good turbo tone, that is audible, but not in your face loud. Also, the test pipes I was looking at are those $145 Z1 pipes. They are 2.4", will this be a problem if my exhaust is 2.5"? Thanks.

entropy31

i think you might want gutted cats instead. so it at least looks like you have cats. or weld the shells of some old cats around the test pipes.

jaffi

Yeah, I did think of that. But, I need to keep the cats for smog testing. And, getting the shells seems like more trouble than it's worth. I don't drive like a complete moron on the roads as you know. Well, with the exception of that one time. The only things as far as cops noticing me that worries me is extremely loud exhaust and blue flames coming out of my exhaust.

Goofyz

Catalytic converters use rare metals in a honeycomb configuration to change carbon monoxide to carbon dioxide and NO2 to N2 and O2, when a car is running well it doesn't produce much in the way of emissions. Most of the pollutants your car produces are when its warming up cause of a couple differnt reasons 1 Cats need a little heat to work best and 2. your car runs rich when its cold (fuel injection is a wonderful thing but it still pretty much uses a choke when its starting a cold engine). Removing the Cats completely will probably not affect your emissions test unless you have a fuel problem like a leaky injector, a vacuum leak, or sticky PCV valves or anythign else that isn't workin exactly right in the way of emission controls. I know Test pipes will flow better than stock converters but thier gains over high flow cats are minimal unless you are pushing A LOT of air/exhaust i.e. really big turbos or an engine that has had a lot of internal work done.

So, short but sweet, id suggest trying high flow cats, and if you want to see a bit more performance from a pressure drop on the exhuast side of the turbo try extrude honing your exhust manifolds.

jaffi

Yes, I know this. Plus, there aren't many emmissions tests that still use cold start. So, your point is well taken. But, $145 for a good set of stainless steel test pipes beats out exhorbant prices on high flows. The fact that I want to change out the tests for cats during test time is because there is a little extra safety net there and also in case they actually inspect the exhaust. Sure, I am skimping on the test pipes, but they are really just plain pipes when you get down to it. Nothing more. As for the exhaust manifold, I won't skimp. As far as I know, there is absolutely no problem with skimping on the test pipes, but there are when it comes to the manifolds. What I am looking for now is more of a good tone. Sure, performance is great, but I am after the sound right now. Like I said, not in your face, but with an amazing tone. I feel that I can achieve this with this setup. That is the crux of this situation. Not the gains (I already know the gains associated with certain mods), but the actual tone of the exhaust. Emphasis on a moderate db level. That is the opinions that I am after in this thread (though I appreciate your input).
EDIT: As for your mention of high boost applications, I say this. I don't like to buy twice. I like to be ready for the future. In the field of performance vehicles, this is very important. No, I am not going to get the multi-thousand dollar stuff if it isn't needed. But, I will get the alternative that will work in most-if-not-all situations. Alas, test pipes.

Goofyz

about the sound level eminating from the back of my Z, i went with a Borla SS exhaust system (cat back), Its not very loud compared to stock, im not sure how it stacks up to the stillen exhaust except that its about 200$ cheaper (i am sure about 1/2 of that is name and 1/2 is quality) The Z engine does tend to resonate around 2500-3500rpm and that is except for really high rpms the loudest your engine will get. I listened to a Z that had straight pipes right off the back of the manifolds, i mean NO muffler no resonator no cats nothing and it wasn't extremely loud, the turbos actually do a pretty good job of muffling sound meaning the natural z would be a lot louder in this configuration than the turbo z. As long as you have a cat back system on, I am sure you wont have much of a noise problem (outside the car) with local police. As you said though you might have a problem with inspection, those guys with the little mirrors can be real bastards, last time i went i had to get a new gas cap cause mine wasn't holding up to thier pressure standards.

1SIKZ

Agreed.. when you have a turbo vehicle, its gonna be a lot quieter when compared to the N/A.. personally I bought my Twin Turbo Z with a HKS Supper Dragger Stainless steel cat back exhaust already there..At first i wasn't a big fan of teh 4-5 inch tip .. but now i love it and id never change to anythig else .. maybe an ANSA sport (FERRARI EXHAUST)

jaffi

But, when I get the test pipes it should fatten up the tone a bit. Plus, it will have still that distinct turbo sound. I got the Exhaust installed the other day (pretty darn easy since there is no rust on any of the bolts). There was a funny smell eminating from it after the test drive. I attributed this to part of the brake in. There must be something on the exhaust itself. I like the tone of it. Not, in your face, but very nice. Just what I was looking for.