TTI headers ready to go in....any advice?

I put mine in from the top down, but I had the motor off the mounts and as high as I could get it. It was a little tricky, but I got 'em in OK. I did not have any of the transmission linkage in place though. That came later.

The bushings I mentioned sit within the header bolt holes. 1 on each corner. I bought them on-line the exact thickness, ID and OD that I needed. As I recall I spent hours scouring the net and found only one place that stocked the exact ones I needed. In effect they reduce the size of the header holes to match the size of the header bolts. There's still enough wiggle room for the flanges to expand from the heat without warping. This is actually what the TTI people recommended when I called and complained about the slop.

Put a header bolt in one of the holes and jiggle it around. You'll see a lot of play. This makes the headers hang low, ie not centered precisely in the hot gas outflow. In fact, if you have the engine on a stand and hang the headers on with some marking chalk, you'll find that there is intrusion of about 1/8" - 1/4" of flange sticking in the exhaust flow.

Maybe you're not picky like me, but I figure if I'm gonna spend $600 on a pair of headers, they're gonna work right. I'm big on exhaust, there's a lot of horsepower to be gained there in a high revving small block.

I used a rotozip grinder to match the head exhaust ports to the headers. Just screw some studs into the heads, hang the gasket and trace the inside holes with a scribe onto the head metal. Then grind off (carefully - keep it clean) any metal that is in the way of a smooth transition from the heads to the headers. You can also do the same with the header flanges but be aware you are losing your warranty if you "adjust" TTI headers in any way.

This takes little work and $$ and you don't need to be a rocket scientist to do it.