Crawling out of the woodwork for this one. Bob of course is right. If your headers to sidepipes are flanged and bolted tight, something is going to go. Usually the #3 header pipe first.
This is only caused if you bolt the tail end of the sidepipe "rigidly" to the frame...this combo is a definate no-no.
Use a large rubber "block" between the hanger and the pipe. Absolutely no problems.
Dalola, has the simplest, safest solution, in my opinion. Remember if you go to solid motor mounts, you should also use a solid tranny mount!
No solids for us...Hundreds of 5,200 RPM launches with slicks and nothing broke yet....except rear ends!
DV