I'm curious after reading a couple of threads......does straight piping really affect performance and mpg? Does it usually cause alot of cab noise? I tow long distances quite a bit and don't want it interfering with my music. :rolleyes:

This is for a stock LB7 with 40K. :)

Usually you won't see much if any performance or fuel mileage gains on a stock truck.

You will probably get a drone in the cab and it will be really loud outside the truck.

At idle its not bad loud at all. While driving it is pretty loud outside, not bad at all inside with the windows up. It you are listening to music you won't even notice it. That is what I see with my LLY. Not sure what the diffrence would be for an LB7 but I would think you would see pretty much the same as me.

I noticed a slighty quicker spool up but I didn't think it was really anything signigficant. At first it thought there might have been about 1 mpg better but it is really hard to tell. It you are thinking of doing this, the main reason should be lowering egt's which it will do between 100 - 150 degrees. Any other benefits like quicker spool, more power, lower mpg will be negligible.

i straight piped my 03 with 4 inch and noticed it was quicker off the line and maybe 1 mpg better. on my edge attitude screen i noticed it dropped my egts about 200 degrees. but at about 2000 to 2200 rpm there is a howl in the cab that is annoying otherwise i love the sound.

My 5" straight pipe gets loud in the cab after 2000 rpm. Most of my cruising is at 1900 and I can't hardly hear it then. With the aFe stage 2 and the 5" straight pipe combined, I gained about 1 mpg. It helped for performance at lower rpms, but don't see any benefits once the turbo gets wound up. It has a nice growl on acceleration, and that makes it all worth it.

would a cutout before the muffler lose too much backpressure?