I have done my homework here and know that a 1 7/8" header is the way to go but I was wondering if anybody could tell me how much power I would be sacrificing here. I am doing a FI build, D1SC 8lbs, blower cam, stock bottom. My buddy offered me a set of SW headers, they are 1 3/4" with a 2.5" y-pipe. How bad do you guys think I will be choking things off, looking for 550rwhp.

 

The 1 3/4" headers are not a problem but that 2.5" Y pipe may be a little small.

 

What size are the collectors on those headers ?

 

That's a good question,

http://www.stainlessworks.net/produc...aders-ls1.html

It doesn't say but if the y-pipe is 2.5" the collectors appear to fit right in. I guess I assume 2.5" collector and Y

 

Talked to SW, they are definitely 2.5" collectors

 

if turbos can make as much power as they do squeezing through a single 3 inch downpipe i see no reason why two 2.5 inch collectors will keep you from reaching your goal. Are they optimal, not really. will they work? sure if the price is right. will bigger headers make more more, yep.

 

What he said ^^^
If you have the money - 1 7/8, if not go with those and upgrade later.

 

Yea ive always wondered how thats possible lol, im running a 3" downpipe myself.

 

Somewhere on the www there is a chart showing how much hp each exhaust size supports, and then it goes into duals and how much they support. I agree with the above, a turbo can make 500+ hp with a single 3 inch.....idk but it works.