Always have had trouble with fitment to this day. I'm constantly having to tweak the y-pipe fitment, but I think I've finished that. Now, the pass side collector v-band sometimes vibrates against the frame rail.
I'm going to drop the y-pipe and see if I can heat the frame rail with a propane torch, then hit the frame rail with an air hammer to dimple it enough to give me some additional space. I'm hoping that I don't have to disturb the header (bolts and gasket).

Here are some present fitment pics.

 

From the side:

 

I don't need much as seen from this close-up. But you can see how any vibration would be annoying. I'm hoping that I can get in there to dimple while the collector flange is still in position. I'll be doing this in the coming days.



The v-band culprit:

 

Ya, I have same problem. Knocks a lot on passenger side at idle and sometimes low RPM cruising.

These headers were developed for an LS7 and I have often wondered if the port position or angle of heads is different enough that the clearance problem goes away. If my LS7 ever makes it into my car then we'll know.

 

OK, dropped the y-pipe section. Here's what it looks like. I'm hoping that I can heat the frame rail enough with a propane torch and dimple the rail (even behind the collector flange) enough to give me 1/3" or so clearance once the v-clamp is back on. As you can see, I don't have to dimple the entire height of the rail, just where the circumference extends (bottom third or so).

 

I have a tiny bit of clearance with the V-band in place. I bought some poly engine mounts a while ago hoping that less engine movement would help some. Never got to the job though. Maybe you can tell me so I can sell them if it doesn't.

 

I have the poly mounts in.
Well, as I half expected, the air hammer was a no go. Switched to a #5 hammer and a flat punch. Progress is slow on my back and can't get a good swing with the hammer. This may take a few days as I only want to give an hour or so per day.
Bottom edge of the rail right behind the flange is difficult, but I will win!

 

Finished, I can get a pencil all around the clamp.

Patience and strength of will needed to do this with torch and flat punch. Of course, a lift would have made this easier - or doing it before install of the header, BUT I did not have to disturb the header that was the goal.

 

I may have to do the same for my passenger side header...... just drives me nuts when it rattles.

congrats on persevering!

 

Glad I saw this thread. My engine is a LS7. I'm still trying to decide between the Stainless Works and the Kooks headers. The main benefit of the Kooks is that they also make a y-pipe designed for the 82-92 F-bodies. There is no y-pipe from Hawks that fits the headers I want to use (1 7/8"), They only have the y-pipe for the "budget" headers setup. (1 3/4").

 

The headers shown in this thread are not the budget ones. The budget versions are slip fit collectors.
Check out the 2" version on Hawks site. This header / Y-pipe version has the v-band connections shown above.

 

Nothing wrong with 1-7/8" primary tube but the LS7 will respond well to 2" primary tube.

The Hawks kit is complete, front to back.
Kooks is a mid-length header. Easy decision here --> long tubes FTW.

 

 

This system should support 750 rwhp easy.
LS engine heads respond very well to exhaust side porting. Go 2"! Especially with an LS7.

Kooks makes good stuff. You could have them make a similar system: 2" LT, v-band flanges, etc.

 

I don't think anybody in their right mind is going to answer "no" to that question. The real mystery is by how much (and only you can decide if you care).

You'll be piecing together your own exhaust if you want 3" dual. Texas Speed now makes a 3" dual for 4th gen cars that might be a decent building block to making it happen. Move the rear muffler hangers & cut off the front pipes and fab in a different Y-pipe.... and it might just nestle in place for you.

I'd call Hawks for the heck of it. Bruce is a wealth of knowledge and they might even offer to make up something for you.

 

Thanks for all the info guys. Been out of the game for a while and my knowledge of the LS/LSX is slim. I'm sure I'll have many more questions in the future. Thanks again.