Corvettelove

Its a automatic and I just want a more deeper throaty sound than my stock setup. Not worried about cats either. Biggest thing is I want to keep my npp cause of the convenience for the lady. So my question is what exactly do I need for my GS? 1 3/4 or 1 7/8? what size mid pipe? Looking at the American racing headers. No plans for drag racing just wanting better sound. I know I will need a tune if I go no cats. thanks

Seadawg

You will be louder for sure, and you should put on high flow cats. Just put 1 7/8 LG Super Pros on mine yesterday, with 3 inch mid pipes, it is wicked sounding with NPP open, but barely louder than stock closed. They give you bypass pipes, but I doubt I'll ever use mine even on track days. It hurt my ears at the dyno pulls with the cats installed.

Corvettelove

so the npp pipes are 3 inch?

Quick Silver Z

I believe LS3 systems are 2-1/2". 1-3/4" header would be recommended for "I just want a more deeper throaty sound than my stock setup". 1-7/8" for making more serious power.

97titan

I have been thinking of doing the same thing. Was deciding whether to go headers or replace my NPP with Billy Boat Fusions.

Intersted in what you decide and your results you get.

FrankTank

For an LS3 motor, unless you are planning big power mods or a huge cam I would just go with 1 3/4 , no need for bigger, besides most of what effects the volume or exhaust note is the cat-back section.

Seadawg

Yea, I went 1 7/8 because I plan to go to supercharged later, and they gave me 423 hp and 425 torque at the rear wheels, to use until that day happens.