I am sure GM made thier LS1 heads to deliberatly flow better. Knowing this, and, the fact that they might want to take advantage if it, they produced better manifolds (ha ha ha, yea, right, but maybe???) ? So, are headers equally important on an LS1 as they are with the LT1's and any other motor for that fact?

 

Well, yes and no? Do headers help improve power on an LS1?? Damn right they do!! But in contrast to LT1's, if you only put shorties on an LS1, you're wasting your time and money. The LS1 manifolds DO flow "decent" for manifolds, in comparison to LT1 manifolds, which are ..... crap??

LT's are the only way to go on an LS1, while I know that even shorties are an improvement for LT1's .

 

What about Pacesetters Midtubes? I was thinking of going Midtubes to keep the Cats in their location...

 

Go long tubes and get rid of your cats or just relocate them on the y-pipe with some high flow ones. I don't think you can keep your cats in the stock location even with mids but don't quote me on that one. I went with LT's and no cats and I couldn't be happier. Check out my car domain page I have a link at the top for a video after the header and y-pipe sway.

 

Like mentioned before, LT1s are crap. LS1s are decent, but the manufacturer has do comply to emissions and noise requirements, plus they have to be cost effective and durable. Aftermarket headers don't nessicalry meet emissions specs, some do but aren't up to oem specs. Also headers, won't last nearly as long as stock manifolds.

 

If you're gonna go to the trouble of getting them, go ahead and get longtubes. I'd never put mids or shorties on anything, but that's just me. I think they're definitely worth it, just get a good catback to go with them.

 

Well, if I go with a LS1 setup, whatever I do in the header department needs to get by the Northern Virginia inspectors without too much difficulties. I have read a few post about long tubes on LT1's, and they have ground clearance issues along with emission issues, so it seems. To be honest, I really havnt looked into long tubes cause mids were good enough for the project I was conjuring up. I am thinking of going with an LS1, and, if thats the case, I have a whole new choice now, not to mention a new learning curve, lol.

 

Well, I have to remain smog legal so its definately high flow cats... I am going with a true dual setup so a Y-Pipe is out the question. Midtubes won't provide any gain whatsoever over the stock manifolds? I was worried about LT's clearance issues aswell as emissions issues... Will I still atleast beable to pass emissions with LT's and High Flow Cats? Or will they notice a difference and fail me due to the cats being out of place?

 

"Or will they notice a difference and fail me due to the cats being out of place?"

you're asking US what YOUR inspectors will or will not notice??

why not ask them.

every state, hell every inspector is different.

and midlenght headers are better than shorties...some tests have shown them to yield almost all the gains that LTs produce with only small differences in either top end or bottom end (don't recall).

a good rule of thumb

shorties - 5-7rwhp
mids 8-12rwhp
LTs - 13-15rwhp

give or take