Rear muffler
 

I recently got my rear muffler cut out and straight piped. I was wondering if this tipe of mod would help or hurt performance. P.S. I would have asked this question before I did it but I didn't know about this site until after.

oh ya sorry to make another post but could I put like a regular magnaflow muffler in place of the stock? Would it help?

:facepalm: read my FAQ in the useful saved post section, sort answer to your question is: help.

1. I cleaned this thread up because you weren't being quite as bad a noob as people seemed to think..


2. with a turbo, the stock muffler will impact your power. a straight pipe is unnecessary though. you can always get a straight thru muffler like this:

http://www.etrailer.com/Merchant2/gr...hrough_500.jpg

Simple perforated core tube in the center. No baffles.

If it's not a turbo car, it doesn't matter and you can leave the stocker.

thank you very much. I don't know what is up with that guy. Needs to grow up.

..... :eek5: ..... I'm being good.....

Any muffler would be better than no muffler. Like y8s said, a straight pipe isn't necessary at all, and in a lot of places will get you a ticket, or at least a lot of angry or funny looks. I've had good luck with Magnaflow mufflers over the years. You never did say if it was turbo or n/a.

oh I'm sorry it's n/a.

Stock would have been fine for power then. But if you want to make it less of an audible annoyance, a Magnaflow or any other kind of muffler would be fine.

oh ok. I'll probly look around at some muffler shops and see how much they run. And does dual exhaust make any difference?

Nope, louder.

When I first got my car, I did some quarter mile passes when it was bone stock. I put the rear exhaust first (pipe and muffler), and confirmed that the exhaust made power. I did some testing without a muffler, and it was a hair faster than with a performance muffler, but the noise was too unbearable.

I also confirmed that replacing the cat for a straight pipe gained a tenth. A full exhaust (header, test pipe, and rear exhaust) gained half a second in the quarter mile.

An exhaust is a worthwhile modification even if the car is stock. If you adjust the timing, do a minor intake modification, and add a light flywheel and clutch assembly, you can gain about one full second in quarter mile ET.

I hope this helps.

A half second from exhaust? Not to say you are a liar... but I think you are a liar. :giggle: I first did a RB header, followed by a cat back with no resonator and swear I lost power, and had to deal with ungodly ricerish sounds. It lasted a whole week before I removed it and sold it. The header is nice though, I still have it.

Well, I think he's correct, RB have dyno sheets before and after their full exhaust (headers back) and it gained something like 9.8hp. Not that it's a lot, but it could definitely cut a second off of a 16-some second quarter mile.

I have no exhaust right now. I can't wait to have a real one with a muffler and shit. Only the ricers think my car sounds cool and they roll their windows down when I go past.

I dunno, I still say it's bullshit. I would like to think I could feel a 10% increase. If anything, guessing maybe 2-3 hp from the header, and like I said, the catback, nothing, maybe 1hp if I had to guess. A second, or even a half, no fucking way. At least in my case. Maybe I got one of the non magical exhaust systems. I mean shit, stock our exhausts are pretty large diameter for what they put out, and we have a factory tubular header. I can't see where there is 10hp to be gained.

http://www.racingbeat.com/PDF/56501.pdf
That's with their filter kit though, but it's still 9.7hp.

http://www.racingbeat.com/4_1%20Head...der%20dyno.pdf
Just the header gained 4.9hp.

Still doesn't make me believe it any more. If it was true, that was the least impressive 10% gain I have ever felt. There is nothing stopping them from telling a little white lie with the dyno, like tinkering with timing and what have you. Either way, my point was I was not impressed with what I felt. I do like the header simply for it's excellent build quality, looks, and sound. RB header with stock exhaust is pretty nice sounding. Nothing against RB though, I probably own $5,000-$6,000 worth of their parts on several different cars.

Did you actually do some testing? Have you ever looked at a spec miata exhaust system?

So your saying that the straight pipe I did helped increased my HP gain? I honestly think it did. I felt a little more power between 2000-2500 rpm range than before. My car felt a little slow in second in that range but changed after the mod.

I worked at a performance shop for 2 years with a Dyno Dynamics dyno, and we did a before/after comparison on a guys 1990 miata. Bone stock he put down 102 whp. With the racing beat elbow intake, obx header, and obx catback single tip exhaust he went up to 116hp. It definitely increases power.