I have an america offshore 3100 with twin 454's with m1 prochargers and bravo drives. I am currently running 30 pitch bravo 4 blades. @ 65 mph im running around 3800 rpms. at WOT im running around 83 @ 5000 rpm's with two people and 3/4 tank of gas. Should I drop down a couple RPM's or is that about right? I didnt know if I could hand a pair of 32's

Something's not right here. You should be in the low 100s w/ that setup. Are you sure the trim setting is correct at WOT?

I was told it would run 104 but I cant get close to that. It is my first Cat and twins (which I love it), but I used the GPS on my phone. Every time I have taken it out I get about the same Data. The motors I were told are pretty much stock except for the prochargers. I thought I was trimming them out pretty good based on the mechanical trim indicators. Would me not trimming out enough make close to a 20 mph difference? Although neither boost gauge works but I def hear them whining. Is it a possibility I'm not building boost?

I bought the boat with the current set up but I was told the motors were pretty much stock top and bottom. I was also told it would do 104 but I cant get anywhere close

Not properly trimmed could absolutely cost you 20 mph.

First off, I greatly appreciate all the insight you all are giving me. On the mechanical indicators I'm trimming to about 7 which is 3/4 of the way down, unless the are not set properly and im trimming less than I really am. I know those hulls porpoise around the 60 to 90 mark, but i never really have felt that yet even at 80, is that an indication im not packing enough to air it out (from not trimming all the way)

I'd try adding more trim and see how it reacts. Does it have tabs? If so, where are you running them?

It sounds like your motors are tired or your pro-chargers are not setup properly. What the gear ratio in the drives? Maybe you have a 1.36 gear? Did the boat have bigger power prior to you buying it?

I had a 3100 with stock 500 efi's and it ran 93-94 all day long with 30p 4 blade props.

454's with chargers should put you around the 100 mark depending on boost/pulley setup.

Tell us more about the boat and we may be able to help you.

Phil

No trim taps, just trimming the oudrives