Up till a week ago, I've been running 3/8 .065 wall Smith Bros. push rods with my Isky .680-.660 soild roller cam w/210-540 ish lbs seat pressure initially and now 245-620 and never really paid attention to it then but started hearing horror stories so I called SB and told them what they sold me 15+ years ago and he was shocked someone even recommended those. I got .120 wall based on several recommendations stating the cam can whip around especially at higher rpm's and create issues and even valve float. Plus on the cam side it's apparently less important weight wise like it is after the fulcrum to the tips of the rockers and I can't honestly say I feel a difference cos with the t-ram this puppy goes past 7000r's quicker than ever.....Track time soon a a 5.99 or better pass soon hopefully to follow.....