Dual Exhaust Suggestions (True vs 1-2)

[AustinD]

So recently i bought a 1994 GMC Jimmy which i fell in love with, but today while testing the 4WD we broke the pipe and have to get that replaced.
So, the prices are $150 to fix it and keep it as is(single pipe), about $250 for one in two out dual, and in the $350 region for true duals depending on which exhaust i get.

the questions are numerous. with a 4.3L V6 would i be able to notice trues over 1-2? what are the lower range benifits of each exhaust (since im not really going to test the high end power)? and what are the effects on gas mileage?


thanks everyone, and i shall post pics of my lovely jimmy in the morning

 

[OscarTheGrouch]

Are you going to be straight piped or have mufflers?

There are factors to consider like the size of the pipe, etc.


The less restriction you have on the outgoing exhaust, the more efficient your motor will run. It's not going to be a huge increase either way however, you are talking about 2-5 mpg usually, and a HP boost.


Typically duals are done for looks and sound

 

[ivtecDOu]

3inch straight pipes nuff said

 

[davidwarren]

the headers and cats are the real points of restriction IMO.

 

[mpshay]

Typically duals are done for looks and sound

I completly agree. Unless you have done a bunch of other mods (particularly on the intake side) all you are really going to notice is the sound and looks. Not that that's a good enough reason. If you are going to do more go for the true duals. If not go for the 1 into 2 with a couple nice mufflers. The best way to pick is to hear them in person. Getting others people commendations is not much help because "good sounding" is pretty subjective.

 

[OscarTheGrouch]

I completly agree. Unless you have done a bunch of other mods (particularly on the intake side) all you are really going to notice is the sound and looks. Not that that's a good enough reason. If you are going to do more go for the true duals. If not go for the 1 into 2 with a couple nice mufflers. The best way to pick is to hear them in person. Getting others people commendations is not much help because "good sounding" is pretty subjective.

Heck, i'd remove the cat converter too if your state doesn't do emissions testing, then just go straight pipe. Some state laws will not however allow a mechanic to remove the cat converter- you have to do it yourself.

 

[Counterfit]

Federal law says you can't remove an undamaged catalytic converter before 80k miles.

And while restriction is bad (mandrel bends ftw), what you really need is exhaust velocity on a naturally aspirated engine, so you don't want to go too big with the pipes.

 

[iGav]

Federal law says you can't remove an undamaged catalytic converter before 80k miles.

Really? Nothing a hammer wouldn't sort then.

 

[OscarTheGrouch]

Federal law says you can't remove an undamaged catalytic converter before 80k miles.

And while restriction is bad (mandrel bends ftw), what you really need is exhaust velocity on a naturally aspirated engine, so you don't want to go too big with the pipes.

Actually, a business cannot remove the converter, however as an individual, you can remove it yourself.

Hell I dont know how they could enforce it anyways. And thinking about it, some vehicles need a little back pressure, though i couldnt tell you which ones or how much. Just run dual 2"s out the back straight off the headers, youll be fine. That's a job you could almost do yourself. Most autoparts stores sell exhaust components etc, its not a difficult job.. well it does involve a little welding sometimes.

 

[Counterfit]

And thinking about it, some vehicles need a little back pressure, though i couldnt tell you which ones or how much.

Not really. Turbocharged cars need as little restriction as possible after the turbo, and naturally aspirated cars need exhaust velocity, which usually results in back pressure.

Just run dual 2"s out the back straight off the headers, youll be fine. That's a job you could almost do yourself. Most autoparts stores sell exhaust components etc, its not a difficult job.. well it does involve a little welding sometimes.

2" would be the biggest I think for duals on a 4.3L engine, although the size could go up or down depending on what RPM range you're usually in.

 

[OutThere]

A bunch of people have suggested removing the cat...a guy I know removed the cat and put straight pipes on his Ford Focus (not quite a 4.3L v6 I know ), resulting in the absolute lamest sounding exhaust I've ever heard. He claimed a gain of 4hp from removing the cat, and wound up getting in deep when the car didn't pass emissions.