Can I use just the downpipe from RRM wth my stock headers? I was just thinking to heat wrap or paint the stock headers. Or can I have an exhaust shop make a custom downpipe? And if I go for a custom cat back should I just buy a muffler, resonator, and high flow cat off of ebay? I just dont see how 2.25 will do any different, I dont think 2.5 would be overkill, I did read that topic so dont bust my *****.

 

with a 2.5 in exhaust you'll loose a lot of back pressure and unless you're going turbo I wouldn't suggest it. Most people stick with 2.25 for a N/A car.

RRM no longer sells just the downpipe, the new setup they sell is the downpipe header combo... Having an exhaust shop make a custom downpipe would probably be cheaper altogether as RRM is fairly expensive. I have the RRM downpipe, (no cat) and the RRM catback exhaust (2.25). It has 1 magnaflow resonator and 1 magnaflow muffler. The setup sounds pretty good but does get a bit tinny since I lack a cat.

All in all, I'm happy with the setup right now, and am working on simulating my O2's so that I can pass inspection in June but that shouldn't be a problem.

 

yea get the RRM H+DP combo its great i have it but im also with you^^^ i also lack a Hi flo cat so it gets raspy from 2K RPM to about 3500 RPM and the SES light is on but im not worried sparkplug foulers can fix that

 

I have heard the stock piping is 2 1/8 so 2 1/4 wouldn't do much more unless I put in a high flow cat and different downpipe. Is the stock cat weld on or bolt on?

 

stock cat on 04 lancer ralliarts is welded into the setup. No offense but anything larger than 2 1/8" is a gain. Granted our stock exhaust isn't restrictive it doesn't hurt to free it up a bit more. I just think 2.5 is pushing it unless you plan on going turbo. But its your car do as you please, there are a couple n/a guys who run 2.5inch setups and don't mind it. I just don't think its practical for n/a performance purposes cause we need some backpressure since we're not turbo'ed.

there are tons of threads discussing exhaust size so I'm not going to argue it anymore. But one thing I will say is if you don't like a really obnoxious raspy and tinny sound from 2-3300 rpms then I suggest a Cat.... Plus highway driving pisses my passengers off but i just tell them to shove it or tuck and roll.

 

A 2.5 inch exhaust shuts the raspyness a bit, but quite ups the resonance thru the car...Im talking about a PROPERLY done exhaust, with its resonator and mandrel bends, and a good muffler..pretty much the muffler dictates how much resonance will get thru in combination tih the ex. piping.

Also, with a 2.5 inch exhaust u can still get back pressure. It has to do with the muffler U install with it. U can always buy a free flow muffler with a smaller diameter on the inside or the tip, not a lot smaller but a bit. That way u make a bit of back pressure higher in the RPMs.... I dont prefer it that way but some ppl do it...so more power to them. What I do is match the diameter al the way to the tip

 

I guess what I'm trying to say is you'll loose low end torque... Or that's what I noticed just going catless... I do get high end a bit more but yea.

 

^^^^ +10, you do loose the feel of torque until u get to around 4k

 

I have a 2.5 borla axle back. I thought it seemed to pull alittle better but that just maybe because of the sound? I like how it sounds though, would recommend it

 

does the CEL come on running catless?

 

Obviously yes. There are limited ways around it...search a bit