2G GSX Downpipe + Catalyst Question

[travs_dsm]

Sorry for this noob question, but I am gathering parts to restore my new-to-me 99 GSX and I have a question concerning the downpipe.

Specifically, if I purchase an aftermarket downpipe, will it bolt on to my Catalytic Converter? I live in Virginia and unfortunately they smog every two years, so I need to be 100% compliant.

What I was thinking of was going with the Apexi WS2 Catback 85mm exhaust with a 3" downpipe. The car still has the original exhaust and it has a couple of holes throughout, so I may as well replace it all while I am under there. Thanks you!

99 Eclipse GSX

 

[DGajre777]

I would recommend an Apex-i N1 cat back system and a short RRE downpipe and their high flow cat. You can buy the test pipe and replace it with a Cat when you go for emissions testing or just leave the Cat on the car.

I'm running a N1 and RRE's long downpipe on my AWD.

Eclipse Exhaust System Upgrades

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Your other option is to buy an aftermarket downpipe, taking it to an exhaust shop and having them weld a cat on the car, but there's no guarantees that you'll pass emissions when you are done. You'll have to talk to the exhaust shop to find out which cat would be best for you, if you go this route.

P.s. it's called a catalytic converter, not a catalyst.

 

[Zdrummer15]

I personally would just stay away from Apex'i altogether. The resonators on their n1 cat-back neck down severely inside and are a significant restriction. As far as the downpipe goes; the one mentioned above is the only one I've ever seen that does not eliminate the cat. You can either go with that or the exhaust shop option. If you go to an exhaust shop it will be cheaper and I would also recommend just getting the downpipe off ebay since it'll be chopped up anyway.

 

[dsm8883]

I personally would just stay away from Apex'i altogether. The resonators on their n1 cat-back neck down severely inside and are a significant restriction. As far as the downpipe goes; the one mentioned above is the only one I've ever seen that does not eliminate the cat. You can either go with that or the exhaust shop option. If you go to an exhaust shop it will be cheaper and I would also recommend just getting the downpipe off ebay since it'll be chopped up anyway.

I would have to say the same.

 

[travs_dsm]

Thanks everyone for the help! I like the RRE short DP with the high flow catalytic converter option. I think I would be legal in replacing my stock converter being that the flanges are nearly rusted off.

Honestly, I haven't found any exhaust shops here in the beltway that aren't total ripoffs. I went to one and they quoted me $1300-$1500 for custom exhaust.

Hopefully, I can get this car sorted out soon, it needs a lot of work: exhaust, new wheels and tires, new water pump and timing belt, and fix the oil leaks (hoping it is a cam seal that I can fix while doing the timing belt.) Amazingly, the body and interior looks great and other than the radiator support and exhaust is surprisingly rust free! I think it is worth saving. Thanks again for the help guys!

 

[DGajre777]

You're welcome! When you get the RRE downpipe, make sure you spray paint it in some high temp paint before you install it on your car.

 

[crash89]

You're welcome! When you get the RRE downpipe, make sure you spray paint it in some high temp paint before you install it on your car.

Just curious, but why would he need to spray it with hi temp paint? Are they prone to rust that bad? The website says theyre stainless steal so they shouldnt be!

 

[DGajre777]

Just curious, but why would he need to spray it with hi temp paint? Are they prone to rust that bad? The website says theyre stainless steal so they shouldnt be!

The entire pipe isn't SS, it is SS till the flex. After the flex, it's not stainless steel and is prone to rust. Aluminized steel has better corrosion resistance compared to plain steel but its not better than stainless steel.

From RRE's site - http://www.roadraceengineering.com/eclexhaust.htm

Our DPs have a 2 1/2" stainless steel first bend with a 2 1/2" stainless steel flex section. They then expand to 3" right after the flex section right under the oil pan area. Why start out at 2 1/2"? If you are running on the stock O2 sensor housing, even ported it is 2 1/2" inside diameter. When the exhaust gasses are hot, they flow better, 2 1/2" is plenty for the first 12". As the gasses cool , bigger helps. By going to 3" after the flex section, we allow this expansion and also allow for better clearance at the front where room is tight. From there they are a full 3" back to the Apex 3" flange with 14 gauge aluminized steel piping. We had some Apexi flanges laser cut out of thick 1/2" steel for a good seal and fit.

 

[jgoble32]

I would recommend an Apex-i N1 cat back system and a short RRE downpipe and their high flow cat. You can buy the test pipe and replace it with a Cat when you go for emissions testing or just leave the Cat on the car.

I'm running a N1 and RRE's long downpipe on my AWD.

Eclipse Exhaust System Upgrades

You must be logged in to view this image or video.

Your other option is to buy an aftermarket downpipe, taking it to an exhaust shop and having them weld a cat on the car, but there's no guarantees that you'll pass emissions when you are done. You'll have to talk to the exhaust shop to find out which cat would be best for you, if you go this route.

P.s. it's called a catalytic converter, not a catalyst.

yeah I was wondering the purpose of the test pipe thanks. yeah still learning