This set up comes factory with 28p 4blade, would 30p lab's help or hurt me with only the 454mpi's

Had a 312 with the 502 mags. Spinning non-labbed 30's. I would think with 100HP less you won't be able to turn them up. What is your max RPM now? Your motors should only turn 4,400-4,600 RPMs if htey are the non-mag 454's.

Its Right at 4650 wot 1/4 fuel 3 people, I have never ran a labbed prop before, I have heard before that if you go with a lab you can go up one pitch .With a lab and with the lower gears in those bravo's turning more torque, it might good to go. just another MPI guy dreaming here

Labbing a prop will get the rpm's up usually around 200 RPM's. If your at 4,650 rpms now seems your right where you need to be. If you want more speed.....you need bigger motors!
what is your top speed anyway? My 502 mag 312 hit 73 on GPS (77-78 on the "dream-meter")

64gps

Try talking to the props gurus on the site but I think you've got all your gonna get. I had 105 HP per side more than you and saw 9 mph more on the best of days. Prop work might get you 1-2 more and for $1,500 for labbed props.....I don't think it's worth the gamble.

and your minimum planing speed will go up, and more than likely low speed bite will suffer as well!

Labbing props on Formulas is a waste of money in most cases and overall performance will suffer a little.Save your money,or spend it somewhere else. My 2 cents

Also make sure your drives are the 1.65's .. 312 502's have the 1.65 ....I am not sure about a 454's might be 1.50 .. Magicfloat might know ....

If he's spinning 28's now, he definitely has the 1.65's

BTW: Do you want a spare bravo upper? I have one left in the garage I kept for my 312. Bought a drive that was only 2 weeks old after a guy hit something and twisted the lower. Pulled the upper gears and put them in a upper to have a spare.