Cat-back exhaust upgrade
 

I have an '04 Monte SS 3.8L n/a and I was wondering if anyone can tell me if there is any actual power gain to a, say Magnaflow, aftermarket cat-back exhaust system? I'm looking to squeeze a little more power out of it without losing the streetability and gas mileage. I'm open to other suggestions to gain some power too. Thanks.

Little to no power gains, ~10HP.

It's mostly a sound/aesthetic modification for our cars.

Okay thanks. That's kinda what I thought. Do you know of anything I can do though?

There's actually zero gain to a cat-back exhaust on this car lol.

Make it breathe better. There's a really bad U-Bend in the downpipe, you can get that removed. The intake is a little boring, you can get a good cold air intake for the car. (coldairinductions.com, zzperformance.com wizaired system, etc.)

The front exhaust manifold is a pretty crappy design. Really poor flow, zzp makes a nice front powerlog that fixes that.

Now the U-bend you say is bad, are you talking about the crossover between manifolds? And the zzp powerlog is that just the front or do you need on for the back too?

The U-bend is underneath the car, the rear O2 sensor slides into it (behind the cat). It's a horrible design but it was supposed to make replacing the sensor a little easier. A ZZP downpipe will have straight pipe with a hole drilled for the sensor instead - much better design.

You only need the PLOG to replace the front manifolds, they make one for the front and rear manifolds but the design of the rear manifolds is just about the same as the rear PLOG, no real restrictions in it, so personally I wouldn't pay to replace it.

Headers ftw

This might help with the visualization of the u-bend. You can also just peak under your car and see it.

Attachment 31029

Alright I know what the u-bend is now. I have the tools and ability to eliminate that. Would it be worth doing?

Some say 100% delete the U-Bend. From what I have read, supposedly it moves the same volume of exhaust as having it deleted. But to be honest, it looks better with it gone and probably adds a little performance bump since the exhaust has less turns to flow through.

I would also personally advise to delete the resonator myself. I did and the Butt-Dyno feels a little extra kick for it.