AudiOn19s

From searching the 1001 posts currently on Rennlist about Muffler bypass pipes it seems to be the general feeling that torque is lost down low in the powerband with the muffler bypass pipes.

I'm curious if anyone has Dyno proof of where the torque is lost and what the "break even" point is to where the pipes are no longer a hinderance.

I have GHL headers and Mufflers on my '99 and at the track it's simply too quiet. If I'm anywhere near loud cars I can't even hear my car and while I generally know where it is in the rev range anyhow it'd be nice to be able to clearly hear my car when i'm driving it at all times.

So...I'm ready to purchase the bypass pipes for track days BUT want to make sure there's no sacrifice in performance. As long as you don't loose torque anywhere north of say 4000rpm then I'm fine...just wondering if there's real world dyno graphs out there to back up my questions.

Andy

grizzy

i will be selling mine-when i get off my lazy butt and put my pse back on
Mike

Tippy

You can simply prove it to yourself. Take the mufflers off, it is only 3 nuts and 2 clamps per side and drive around. Trust me, it will be a terd.

AudiOn19s

Till what RPM?...I doubt my butt-dyno will be able to tell where the torque loss stops? Sure I'll know there's less torque down low...but I never questioned that. What I'm curious to is if the torque loss is all gone by say the 4500rpm mark, 5000rpm mark? etc.

My only intent is to use them at the track and I'm looking for data prooving that they're a worthy track mod and don't decrease HP / TQ in that setting as well where the motor will not likely see < 4500 rpm. I'm all for taking weight off of the back of the car...I just don't want to sacrifice performance at the same time.

Andy

Tippy

I am not sure, but you could easily just drop the mufflers and see for yourself. It is like 15-20 minutes to take them off, air ratchet even faster.

himself

I run my MY00 on the track with bypass pipes. There is no big loss at low RPMs (since you are almost never there) and it's awesome in the high RPMs! And (as a practical matter) - it's a DE, so who cares about low end torque. Seriously, what "performance loss" are we dealing with? You're not racing anyone and you're not being timed. So what if you are 2 seconds slower (if you actually are...)

Don't let the "lose torque" propoganda sway you. Just run without. It's loud, it's fast, and it's fun. And fun is what it's all about.

The only potential downside, is sometimes it's hard to hear your tires talking to you. But this has a counter benefit -> you must develop your backside sensor a little quicker

Also, if you don't wanna pony up for bypass pipes, run around with the PepBoys mod (aka the $7.50 mod) and test for yourself. But, just FYI, you can get a used set of Fabspeeds for around $200 bucks, maybe less...

-td

AudiOn19s

This is some of the feedback I'm looking for. I read these threads about loss of torque and just wanted to make sure it only effected the lower rev ranges of the motor where I won't even notice it at the track.

That what I"m getting at..as easy as it is to get the mufflers off of there and save weight on the back of the car IF there really is a performance decrease then I question if it's really worth my time....I'm likely blowing this out of proportion...just wish there was data to back up my questions....looks like I'll try the pep boys mod and find out for myself.

JC3D

On a similar subject, What about taking out the cats? I have gemballa mufflers and they sound good, but looking for something a bit louder. Are the cat bypass pipes louder or quieter than the muffler bypass pipes? Loss in torque?

Tippy

One thing I did notice so it must be pretty substantial is, is the rear felt lighter and more nimble. That was definintely a plus.

aben8057

If you are going to do the by-pass muffler mod, I would highly recommend the SSK in parallel. It completes the "fun" factor driving experience. Yes you loose low end torque BUT they know your coming..and -25 lbs.

penguinking

DE car here as well - i don't care about the hp loss. it still feels and sounds AMAZING.

td873 - i am in agreement with you. though i must say even sans mufflers, the car is quiet in comparison to most race cars - spec miatas, 944's, etc...basically anything with a straight pipe. i love it best for hearing the downshifts when i heel/toe. what a beautiful sound to hear the engine reving while going down 3 gears !

mufflers weigh ~30lbs a piece. thats ~60lbs total that you remove that was hanging past the rear axle. critical weight savings, i'd say, though it is probably diffcult for me to say THAT was what made a difference. i think we all did it for the sound.

a catless exhaust would get you pulled over instantly on the street. too loud.

JC3D

So removing the cats would be a lot louder than removing the mufflers?

himself

No. It's a double dip. Keep in mind that the mufflers will muffle, that's their job. That is, if you have no cats but keep the mufflers then you wouldn't be very loud. You need to remove both.

In order of loudness (less to more):
Full exhaust (muffler + cat) [eh, so-so]
Muffler by pass (with cat) [pretty loud]
Muffler and cat bypass [um, you're getting a ticket in the city loud ]

-td

JC3D

What I meant was remove the cats but leave the mufflers on.

penguinking

he did answer your question.

practically, i havn't seen that done because if you're gonna remove the cats then you're probably in a position where you dont care to have the mufflers on either. at this point you'd just be experimenting to see what makes a less loud of a noise.