I'm getting ready to order headers for my 04 ls1 gto. I notice there are 2 sizes of header. One is 1 7/8 and the other is 1 3/4. Whats the difference other than the size. Will either work? Are there benefits over using one or the other?

 

1 and 3/4ths should do you just fine. That seems to be a popular one with the GTO's from what I've seen so far. What kind of headers were you considering anyways? Do you have the rest of the exhaust the follow suit with it? - Otherwise you're kind of skimping out on yourself.

I'd go with some SLP's if you can afford it.

Btw: if you've got 1 and 7/8ths and you don't have a huge amount of mods to support the airflow, you'll bottom out some of your low end torque. 1 3/4ths will do just fine if you're just doing an exhaust swap and even if you're doing other mods. I would only consider moving up if you did some very serious alterations, but even then the 1 3/4ths perform well. No reason to replace the same part twice if avoidable.

 

I went ahead and gto pacesetters :flame suite on: I got them jet coated and also ordered a set of jet coated catless mids.

 

think most of the guys around here go with the pacesetter headers for the ls motors and have been happy with them.

 

Those are nice as well. I'll go along with this suggestion.