I got a 09 Balt with a short ram intake ported tb and I tuned it with hptuners. My question is will a header and down pipe make a noticeable difference. I plan to go catless or just gut the stocker if a dp won't gain any over a gutted stock one. I'm not looking to make a race car just a nice dd that's fun to drive. I've also got one of the cheap dc sports mufflers I bought for it. With no cat will it sound horrible with that muffler.

 

When i got my zzp header i noticed a small difference without a tune. All i had back then was 2.4 tb, injen cold air intake, and full 2.25 inch exhaust. Adding the header felt like it had a bit better throttle response. I dont have a downpipe because i forgot to get it haha. I would think the dp would make a difference because the stock dp has such small piping.

I would say it will make a difference after retuning it. As for running catless i dont like how loud exhausts sound anymore but im just getting old lol.