gas mileage and exhaust?

[Aharami]

anyone know if gas mileage goes down if you install an aftermarket catback exhaust system?

also, is there any noticable performance gain from this?

 

[MercenaryForHire]

Originally posted by: Aharami
anyone know if gas mileage goes down if you install an aftermarket catback exhaust system?

also, is there any noticable performance gain from this?

15HP to the wheels, I hear.

- M4H

 

[yakko]

My cat won't come back after the exhaust from that Taco Bell got to him.

 

[Aharami]

anyone hear anything about magnaflow exhausts?

 

[Aharami]

Originally posted by: yakko
My cat won't come back after the exhaust from that Taco Bell got to him.

LMAOROFL!!!!!

 

[BCYL]

Originally posted by: Aharami
anyone hear anything about magnaflow exhausts?

Magnaflow is a decent brand....

As for your questions, totally depends on the type of car you have... so it would be helpful if you post the car you are planning to do this on...

 

[Aharami]

2000 GTI VR6

 

[Ladies Man]

what car?

mileage decrease will be hardly noticable, as will hp until other changes are done.

 

[Aharami]

i did a google search....and i get conflicting results

 

[Vic]

Theoretically, it should either have no effect or should go up very slightly. That and any performance gains would depend on the particular car. Many people see their gas mileage go down slightly after installing a new performance exhaust, but that's usually because the new exhaust causes them to drive a little more... uh, spirited

 

[Aharami]

what if i get a catback exhaust along with a cold air intake. would that give me a more noticable performance gain and/or increased gas mileage?

 

[BCYL]

Minimal difference in performance and gas milage...

In fact, you might notice a performance decrease if you use the wrong exhaust system (eg. Exhaust is too big, thus you lose back pressure resulting in loss of low-end torque)...

 

[MercenaryForHire]

Originally posted by: Aharami
what if i get a catback exhaust along with a cold air intake. would that give me a more noticable performance gain and/or increased gas mileage?

Here's your rule of thumb - If you can bolt it on or buy it from Pep Boys, it's not going to help much.

The usual N/A engine tweaks are IHE - Intake, Header, Exhaust. Out of the three, the header will give you the most gain - and even that isn't much. Maybe, maybe, on a good day, you'll get 15-20 to the wheels if you add quality of all three.

In a turbo engine - like a Subaru, for example - you can get better results if one component is a "chokepoint" - but in order to have a choke point, you need to be making power to start.

- M4H

 

[Zenmervolt]

Shouldn't make much difference in anything except noise suppression. Almost all of the restriction in a modern exhaust system is in the header design and in the catalyst itself unless the exhaust system is really, really, really crammed in there.

ZV

 

[Aharami]

Originally posted by: Zenmervolt
Shouldn't make much difference in anything except noise suppression. Almost all of the restriction in a modern exhaust system is in the header design and in the catalyst itself unless the exhaust system is really, really, really crammed in there.

ZV

noise suppression? i thought exhausts are mainly meant for noise!?

and btw, im not lookin for an exhaust that's really loud or emits a deep base all the time. i want something that wont give me a headache.

M4H, im not buying any of these at pep boys. was looking at magnaflow exhaust and neuspeed cold air intakes

BCYL, do you know anything about magnaflow exhausts? are they too loud?

 

[Vic]

Originally posted by: MercenaryForHire
Here's your rule of thumb - If you can bolt it on or buy it from Pep Boys, it's not going to help much.

The usual N/A engine tweaks are IHE - Intake, Header, Exhaust. Out of the three, the header will give you the most gain - and even that isn't much. Maybe, maybe, on a good day, you'll get 15-20 to the wheels if you add quality of all three.

In a turbo engine - like a Subaru, for example - you can get better results if one component is a "chokepoint" - but in order to have a choke point, you need to be making power to start.

- M4H

Now, now... let's not spill from one thread to another.

The reason why headers don't do much for performance gains in the WRX is because the factory headers are already pretty well-designed in the first place. Turbo engines require not only good exhaust velocity (just like NA) but also that the exhaust heat efficiently reach the turbo without radiating too much out the pipes (because heat = energy). Therefore, performance replacement headers in a turbo WRX would have to be thermal coated and/or heat shielded just like the stock ones are, and that gets expensive for an otherwise minor performance gain. Now if you had a lot of other mods and tuning, and the stock headers became the bottleneck, then you might want to have them replaced, but that probably wouldn't happen until you're going for more than 300+ hp.
The best mods you can do to a WRX is to get rid of the 2 cats in the uppipe and downpipe, as exhaust velocity and heat powers the turbo (uppipe), and differential in pressure through the turbo (downpipe) creates boost. Other mods would follow if desired.

All cars are different. When looking to mod any car for performance, the first thing you want to look for is whatever is holding performance back the most and do that first, but recognize that each mod must be compatible with either the next mod or whatever is to remain stock. In a way, it's just like upgrading a computer.

 

[geno]

It varies from car to car how much of a difference it'll make - what kind of car are we talking about here?

 

[Vic]

Originally posted by: geno
It varies from car to car how much of a difference it'll make - what kind of car are we talking about here?

Look up. 2.8L VR6 12V -- an engine that doesn't mod well for extra performance in the 1st place.... but they do sound awesome with the right (not too loud) exhaust.

 

[Aharami]

Originally posted by: Vic

Originally posted by: geno
It varies from car to car how much of a difference it'll make - what kind of car are we talking about here?

Look up. 2.8L VR6 12V -- an engine that doesn't mod well for extra performance in the 1st place.... but they do sound awesome with the right (not too loud) exhaust.

and do you have any suggestions on what is the "right (not too loud) exhaust?"

 

[PowerMac4Ever]

I recommend Dynomax, they have good prices on mufflers

 

[MercenaryForHire]

Originally posted by: Aharami
noise suppression? i thought exhausts are mainly meant for noise!?

It's called a "muffler" not a "loudener", dammit. I hope you're joking.

M4H, im not buying any of these at pep boys. was looking at magnaflow exhaust and neuspeed cold air intakes

The point is that you can buy them at PepBoyZ - and they're pretty much worthless on that engine like Vic said.

- M4H

 

[TechnoKid]

Aftermarket cotton-gauze air filters like that of K&N (and some foam type elements), have been shown to not filter the air as well as paper media. This leads to more dirt in your engine oil. So, its a trade up; more power by getting a K&N, or less dirt and less wear on your engine by sticking to stock.

Magnaflow make nice exhausts. You might have troulble finding an exhaust shop around that does mandrel bending if you decide to go custom piping.

 

[Aharami]

Originally posted by: MercenaryForHire

Originally posted by: Aharami
noise suppression? i thought exhausts are mainly meant for noise!?

It's called a "muffler" not a "loudener", dammit. I hope you're joking.

M4H, im not buying any of these at pep boys. was looking at magnaflow exhaust and neuspeed cold air intakes

The point is that you can buy them at PepBoyZ - and they're pretty much worthless on that engine like Vic said.

- M4H

yes MUFFLERS are meant to muffle noise. but thats stock. i wasnt talkin about that. aftermarket catback exhaust systems have resonators that generate that throttly sound. most people get aftermarket exhausts (not just the muffler) for that throttly sound. if it didnt produce a louder sound, noone would get them cuz they might as well stickwith their stock exhaust

 

[Vic]

Originally posted by: Aharami

Originally posted by: Vic

Originally posted by: geno
It varies from car to car how much of a difference it'll make - what kind of car are we talking about here?

Look up. 2.8L VR6 12V -- an engine that doesn't mod well for extra performance in the 1st place.... but they do sound awesome with the right (not too loud) exhaust.

and do you have any suggestions on what is the "right (not too loud) exhaust?"

I don't own a VW, but the consensus on VWVortex.com seems to be the magnaflow. It's just a cosmetic mod for the most part though, don't expect much of a performance improvement.

If you want it, I say get it. Sporty cars should be heard before they are seen

 

[Evadman]

Originally posted by: Aharami
yes MUFFLERS are meant to muffle noise. but thats stock. i wasnt talkin about that. aftermarket catback exhaust systems have resonators that generate that throttly sound. most people get aftermarket exhausts (not just the muffler) for that throttly sound. if it didnt produce a louder sound, noone would get them cuz they might as well stickwith their stock exhaust

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