here is a stock throttle body for a 500 efi in perfect shape I installed a mono blade and i dont need this one any more. $125 or best offer.

Did you see a difference. When I redid my stag. 390 I went to the AZ. speed and marine kit. and it only made 6hp and 11fpt.

It,s hard to say i am running a procharged 540 and i didn,t like the web in the middle of the stock unit . and the cfm rating on the mono blade is greater than the 500 throttle body so i figured what counld it hurt at 6000 rpm. i didnt have a chance to dyno the motor to compare the two.