With the power potential of the 6.0's, I'd definitely go to a 1-3/4" primary pipe. You barely breathe on those engines and you're sitting at 375-400rwhp.

Installed a set of these the first of the year and love them.

How was the fitment on your Denali? I know we have different trucks, but it's still comforting to hear other people with success stories.

Here is another question... my truck has the same wheelbase as the SS, so if I purchased a set of "bolt on" SS headers, and an SS cat back should it all "bolt on" with no issues.

BTW does anyone have any details on the inner diameter of the primaries of headers like the supermaXX and the pacesetter? I would imagine that if these truely are the EXACT same design as the old dyna's then they would be 1 5/8" as well right?

I forgot to add that i had some spare DEI heat swap sleeves that I used on my #5 and #7 plug wires. about 100 miles logged on the new headers and the wires are in great shape.

hope this helps.

I checked the promaries on the set i recieved and the flange appeared to be 1 5/8's just like everyone else has measured.

put mine on today fits really good the only thing i had to do is clear the front yolk but its real close on the passenger side frame but its not touchin so all in all im really happy with them and the price made it even better

What year truck do you have? My front yolk is no were near hitting.

02 it barely was hittin these things must be inconsistant as hell some are a perfect fit and some have nightmares but i cant complain

Well I hope I have good luck when I buy them in a couple weeks. Having to take a hammer to them does not sound like the ideal situation. I can't imagine having dented pipes helps the exhaust flow...
I just bought a GMPP "performance" cat back in hopes that it will sound great with the the fake cats on the OBX headers. As it sits I think the exhaust is a little too reserved for my tastes, but I really don't want do deal with a lot of drone either.

Those that have had fitment issues, did the mid pipes still line up with the stock cat back OK? I would think that if something is off it would only be exagerated the further away from the motor you get.