It's my belief that when inserts collapse it's a viral thing, i.e., when one area of the foam breaks down, over time it grows through the rest of the foam. So I always trim the outside corners of my truck foams, since where the sidewall meets the carcass has a bit of curve to it I don't want to get that edge pinched.
But that's just me
Faster Than Factory
On The EDGE Racing, est. 2001 - Home of the 524, the Silverado Slammer E-MAX6X6, and the Sand Dollar prerunner
Mike Budzien | facebook.com/OTE.TheMissile | RIVCO Products | The RC Corral | iRacing.com