Aftermarket downpipe fitment and motor mount issues

[87GN_70GS]

In trying to get an aftermarket 3" DP installed on an '87 T, I noticed that the rear of the DP was hitting the frame. There is no "slop" in the mounting bolts to allow the rear of the DP to go upwards. ( I left the bolts very loose). So I started looking at the possibility of the motor mounts being the issue. I have new aftermarket (Pioneer) mounts on both sides. I compared them to the original worn (squashed) GM mounts that I took out. I measured the passenger side worn GM motor mount and got approx. 2-1/2" from center of the frame pad bolt hole to the backside of the mount where it bolts to the engine. On the new Pioneer mount I got 2-3/4" for the same measurement. So in my case, the new mount is actually 1/4" taller than the worn one. So this should be helping me. The driver's side measured about the same.

Anybody else experience this or have any measurements?

I have also replaced the headers with Poston's so they may have introduced an angle where the turbo mounts that is compounding the situation.

 

[salvageV6]

I have a THDP and Postons headers.

They both fit fine with my flat old broken stock motor mount as well as the new HR Parts drivers side motor mount, if anything the pipe was too high near the heater box with the stocker, nowhere near the frame.

New HR Parts mount drivers side helped about 3/32" or so lower.

I enlarged the holes to try to lower it a bit and to line up better with a badly drilled and tapped hole in my Precision PTE51 turbo exhaust housing.

Now I use studs and have no issues taking it on and off.