Upgraded to AFR ALUM have a roller cam and angle milled 034 castings with titanium valves 7/16 studs raised guide plates matched springs 2925 intake that is only for these heads. 750 without rollers and cam add 150 if bought together 800. Also have me mechanical ready 180 dart heads complete 500. Yep bolt on ready 49 cc darts. 386-837-8048