Check it out for those interested in our +5mm strokers also available +7 and +10mm. Normal exhaust port on a 421 cub with Blaster Pistons 68bore/58Stroke 115 rods sets Ex port at 196deg (+ or minus 1deg I've seen) with the +5 stroke it raises the piston .020 above bore with .018 bases gasket. One could skim another .020 off a dome to upgrade or a thicker base gasket (will lose squish tightness by .020) so on the plus side with a std. .018 base gasket it bumped our port timing up to 198deg with out doing anything to the exhaust stock exhaust port timing set by the Manufacturer of the cylinder. Converts the Engine to a 428 cub. Don't tell your friends  this can be equivalent to +5-7hp and 1-2Tq gains as a bolt in mod on a un ported cub. Keep in mind transfers and Aux port also go up 2 deg. Starting price from $1099.99. You give us your specs and we can custom build for what fits your Horsepower.