If you are starting with a 4v then you do get more power for the money than a 2v. But you're not. You are going to spend the money first to make it a 4v and then spend additional money to make it faster. You would be better off getting a supercharger or a turbo.
ProCharger P-1SC, 9 psi, STD 396/383; Uncorrected 388/375; SAE 383/370.
USAF 1969-1996: Vietnam veteran. Aircraft maintenance. ICBM Operations. Research & Development.
Also own: 1997 Harley FXDWG, 1998 F-150, and 2002 Corvette LS1