I have twin hp525EFI converted to hp500 carburators, imco-2 lowers and stock bravo 30" props in my 1998 29 Outlaw. It runs 80mph @5100rpm, but I think there is more power available if engines run little higher. Props are maybe too heavy, but cruise speed is good, 50mph@3600. I don't want to loose cruise efficiency because gas is expencive in Finland. Could labbing help to get rpm up to 5500 without losing cruise speed significantly? I have think extension boxes too, any experiences? How about bigger carbs? Perhaps 15-25hp/engine? I like to see 85-88mph....

I had a 29 outlaw with HP 500's and low 80's is what it ran...Boxes will make the boat "feel" longer, if they're going to be of benefit, propshaft height has to go up too.. you already have 2" shorties so that is going to be hard to accomplish, unless you buy - 3 IMCO's or find some 3" raised IMCO boxes, which also requires raising the engines... That being said, I doubt you'll net a 7 mph gain from it...I doubt a bigger carb will do anything, what will work is getting your power level to around 600 hp, which will require engine mods or larger engines.

I have not to rise engines if change drive shafts to cardan shafts with double u joints. Then X dim can be adjusted. I think there are too much job to fit boxes, must take engines out... Maybe try just prop modification first or take more power. I think, engines can make 550, because hp525efi, only intake mods give additional 25hp. Tall brodix single plane intake and good carbs can make same, perhaps.

ksalmine

Raising the drives is going to increase the 15% you now have.
Labbing the props with the correct recipe is a option. It will need to be done to harness some slip and improve boat attitude.
We would be looking to decrease slip by 1% and increase rpm by 200. This combination will gross 3-4 mph.
Prop work alone will not get you 5-8 mph. We can get you the 500 rpm you desire but the efficacy will definitely go backwards.

Let us know if we can help.

Brett