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Downpipe with stock exhaust

16K views 18 replies 13 participants last post by  AndyMac204 
#1 ·
I recently bought a 14' si coupe and was wandering how much power would be lost if I just did dp,cai,and tune? Basically I'm thinking of the rv6 or full race dp, acuity cai. Or should I just go with a cat back as well? My main concern is noise, just really excessive, and clearance. (I did use to have 3" on my 99si as well. )since i plan on lowering eventually as well. Any feedback would be awesome!
 
#2 ·
Get the invidia q300 it's damn near as quiet as stock. I'm lowered about 2.5 inches and I do drag it across things from time to time. If you know how to drive lowered cars its not an issue. I've done just a header to stock exhaust before on previous cars and the bottle neck is noticeable.
 
#3 ·
I've got the RV6 catted DP with stock exhaust. Also supercharged. My car is pretty close to stock-sounding, except for the whine of the supercharger of course.
 
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#7 ·
I would lean towards no, like Vit told me, the catback really doesn't do much besides change the tone of the car. If you're running N/A it really isn't a noticeable difference from stock exhaust because the stock exhaust is 2.25 in diameter compared to 2.75... It's got a "sporty" exhaust from factory.
 
#6 ·
I asked this question to VitViper himself, he told me the DP adds about 90% power gains (when talking about DP, Intake and Catback). The intake adds about 5% and the catback adds another 5%. So if anything skip the exhaust. I ran RV6 catless DP and intake with stock exhaust, it was fine... but the NON deep tone with rasp was ugly imo. So I threw in the catback to get a nicer deep tone (Q300).

Hope that helps.
 
#9 ·
I have the RV6 catted DP on stock exhaust and stock intake with resonator delete. It is definitely louder than stock but the volume is still in the pleasant range when partial throttle. WOT is actually a bit too loud for me if there are walls on both sides of the street and I have the windows down. If I have the windows up, then the volume is even closer to stock.
On a volume scale of 1-10, a civic lx is 1, civic si is 2 being twice as loud, then Si with RV6 catted DP and intake resonator delete is about 3-4. I don't think I would want any louder because I like "quiet" cars.
 
#13 ·
Seems to be varying opinions on this. I think so long as your tuned for your intake side, your good for this minor exhaust side change. The intake with the MAF is what gets really picky to changes.
 
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#16 ·
Im running full race cated DP with oem mid pipe finished of with the injen axel back. Im getting it tuned soon. The car sounds amazing imo and i couldn't be happier. I also have the hasport top and rear motor mount which definitely impacted the sound of the engine.
 
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