I'll check and see what intake and throttle body I have and get back to ya'll. I know its is a four barrel style throttle body.Which one is better ?

I did a full build on twin 350 mag mpi's. You need to build the torque on them to get them to spin the prop. Pushing around 600 on each of mine

How can I check to see what intake and throttle body I have ? Right now I'm seeing 4500 rpms also. Is there a good 3 blade prop ? I'm running a Rev4 19 pitch now

stock 350 mag and whipplle
 

Hi Craig, did you mean to say with "stock cam and pistons and vortec heads"? i have been running a super modified 350 mag with a procharger MS1. nothing but trouble . rebuilt it for 3rd time and detonated again as i can t seem to find a re-builder or marine mechanic in my area that can tune the EFI properly . i have a line on a slightly used 350 mag. I would just keep my stainless marine exhaust and and 7 quart baffled oil pan but otherwise not touch the stock. I have been told a Whipple 350 kit can be put on stock to boost it to 465 Hp with good low end torque. Whipple has a stock flashing to tune the EFI chip that works apparently . it does seem to check out, but i wonder if that was your experience and if it still running and reliable.
Thanks for any info

Dalt,

Craig also hangs out on "Donzi Marine Restoration Society" facebook page. He is running 95 mph in his 18' Donzi Classic. No problems with his motor. The Blackhawk drive has a high x dimision also.
Look him up,he will help you with what questions you may have.

Mark Oltjenbruns

Let me know if you want to sell your old motor,I may be interested, Where are you located ?