Right now my exhaust is bone stock. I have a 1 chamber Flowmaster at home that is 3" in and 3" out. I am thinking about slapping that on there for a better sound. I am going to leave my cats on and probably just run a dump for now then a side exit in front of the passenger tire. My question is will there be a huge decrease in back pressure and if so will it hurt my truck's performance and gas mileage?

 

No.....

 

backpressure is always bad. Scavenging is what you want you want to maintain.

 

your cats will keep everything moving. now if you took them out, you would loose velocity, and low end power. Since it would move the power band up. Also if you took the cats out and only had the 1 chamber it (to me) will sound like ***. I did this a few years ago on one of my old trucks.

 

I just went down and had it put in. It was actually a Melotone muffler. It sounds really good and real smooth. It is barely noticeable at idle and has a real smooth rumble through the gears. At open throttle, it isn't deafening at all. I expected it louder since I used to have it on my '92 z28 but that didn't have cats. All in all, good choice. Oh, it is only 6" long and I can now run a pipe out before my rear tire with a Corsa tip.

 

i ran a 18" magnaflow with the stock locations didnt lose a thing and got a better sound out of it. i have it tuned via hp and my performance hasnt dropped a bit.