This on a street driven foxbody with a DFI(Fast Classic Bank-to-Bank) 427W, 10.5:1, TEA 240cc HPs, fully ported SuperVic with Dominator flange making just over 500rwhp with a mild solid roller. Will be running e85. This is a Pony Down kit which comes with the 60s standard and the next step up is to 72s, 76s, or 78s which is a $399 upgrade no matter which size is chosen. Again, it is 99% street car. I haven't been to the track in about 5+ years. Would like to go back but probably will never go that often. Will the 60s get me into the 700-800rwhp range and is it likely that there will be backpressure issues?