[DanEC]

Lippy, did you test fit all of the individual headers at the slip joint before installing and did they seat with some wiggling in? Are they stainless or ceramic coated?

I have undercar collectors but I think the header portion and slip joint part ot the collectors are the same - I'm not 100% sure. I also ordered mine in bare steel from ERA and sent them out for ceramic coating. They coat the inside also for durability and swore it would not interfer with the slip joints. That was a story pretty easy to see through and sure enough with inside and outside layers of ceramic coating I couldn't even get them to start. I marked where they had been test assembled with the tabs before coating and wrapped the exposed area above the connection with masking tape and then sanded the outside coating off of the header and the inside coating off of the collector until they would slip into place without too much effort. I used drum sanders inside the collector area. When assembled none of the sanded area is visible.

Then I liberally coated the collector side with Walkers sealent. I left the headers very slightly loose on the engine - I just lightly snugged up the bolts so there was still a little wiggle to the pipes to ease alignment. Then I started the collector over the pipes and started working it up by applying pressure and slightly twisting the collector back and forth. That generally got mine up within a 1/4 inch or so and then I put some masking tape on the bottom of my collector and rapped it a few times with a rubber mallet. That got them up to where I could use a punch through the tab holes to ease the pipes up the last 1/8 inch or so and I could get the bolts in. I used a couple different size steel punches to work them up the last slight amount.

With the undercar collectors, rapping on the bottom of them from below was pretty much driving them straight up on to the headers. I don't know exactly what is different on the side exhaust headers to allow them to come out slightly higher through the rocker panel - but if it's pretty much a straight line to the heads, some twisting and rapping on the collector with a mallet should get them in place if they did individually test fit OK.

I guess I should add it probably is possible to dent exhaust or collector piping with a rubber mallet if hit sufficiently hard. You kind of have to use a little judgement in how hard to rap it.