Rebuild or upgrade components 454 HP420???
 

I own a 1989 357 formula twin 454 w/ HP420 motors and TRS out-drives. Stock compression ratio. The motors have a Hirel aftermarket Multipoint fuel injection also. Ehaust is a stock Merc water mix thru hull system. I am considering several options this winter. Other threads seem to state that a cam change would not make much of a difference. What kind of power can be made from this setup? I would be interested in projects people have done from cam upgrades to full top end changes or more.


Who has some knowledge???