My 312 Fastech has twin 454mag MPI's, gets on plane fast and runs 70-71mph. I'm hitting the rev, limiter now, In about 2 weeks I'm putting on my Gill off-shores and my Vortech breaters. Would you get the ECM re-programed to bump the rev and some more ooommmfff. Or have the props reworked OR jump up in prop size? I have 28 Bravo-1's Or all the above?

both try 30 labbed have Tyler Crocket give a tune after you install your parts do all your testing with full tank ,if your on the rev real hard you allready need props

call brett @bBlades he will help you with your props he did mine for me and they worked great! he knows the boat well.

I would look toward the props. Test a set of 30's and go from there. BBlades should have some you can test, then you can talk to him about what would be your best option.

If you are only going to do one or the other, do the prop. If you are going to change the ECM at some point do that first. You may have to change the prop pitch anyway with the ecm change. You wont have a baseline to work with until you run the boat with the new ECM, then you will know what you need in a prop.

Seems like a lot of prop slip. Plug in your numbers on this site. I run 70MPH at 5000 RPM with a lab 25 Mirage. You have over 19% prop slip. http://www.rbbi.com/folders/prop/propcalc.htm

Onother thing, I would get your setup the way you want it first. Then tweek on the props, otherwise you may have to have them redone after you add more power.

Every 312 I've heard of has 1.65 bravos (mine did too)

If your close to the rev limiter, I'd work the props and agree labbed 30's is probably the way to go.

I assumed 1.5 as a stock ratio, 1.65 would make more sence. That would be more like 12 or 13%.