Handleing Or Speed Help

[PLACECRAFT20]

THIS MAY NOT BE IN THE RIGHT SPOT BUT HERE IT GOES. I JUST INSTALLED A 420HP/425FT/LBS ZZ4 GM CRATE MOTOR IN A FRIENDS 02 20' BAJA OUTLAW. IT ALSO IS RUNNING A 150HP NOS SHOT ON A ALPHA DRIVE. THE PROBLEM IS WHEN YOU GET OVER 70MPH IN THE BOAT IT IS INCREDIBLEY SQIRLEY TO DRIVE. THE WATER HAS TO BE PERFECT FOR A SPEED RUN. SO FAR WE HAVE SEEN 74.5 ON THE GPS BUT WE WERE BOTH SCARED TO DEATH. ANYBODY RUNNING ONE OF THESE OR HAVE A SUGGESTION SUCH AS A DRIVE SPACER OR SOMETHING. I AM A JET BOAT GUY SO IM PRETTY DUMB ON OUT DRIVE SET UP.
HERE ARE SOME PICKS. THANKS MITCH
http://www.***boat.com/image_center/data/522/252duke1-med.JPG
http://www.***boat.com/image_center/data/522/252duke3-med.JPG
http://www.***boat.com/image_center/data/522/252duke2-med.JPG

[celeb1]

Alpha drives become unstable over 60 mph. You might calm it down a bit with a nose cone on the lower. When you blow the Alpha drive switch to a Bravo. The right prop might make some slight inprovements.

[PLACECRAFT20]

WE HAVE TRYED A 4 BLADE PROP AND WENT BACK TO THE TREE BLADE. THE FOUR BLADE MADE THE CHINE WALK WORSE. WE EVEN ADDED A SET OF TRIM TABS. I DID NOT THINK ABOUT A NOSE CONE. I AM BEGINNING TO THINK THAT WE HAVE REACHED BAJAS SPEED LIMIT.

[1BIGJIM]

What pitch of prop are you using, and RPM?

[PLACECRAFT20]

we have tryed about four and settled on one. ill have to look at the boat tonight to see which one it is. we are lucky in the fact that marine propeller warehouse is located in town. he has been letting us try whatever we need to find the right one.

[HP350SC]

Is the Baja a stepped hull? My old 20' v-hull was a non-stepped hull and got unstable and would chine walk at 72mph, especially with high trim settings. You have probably reached the performance potential for that hull. Unless you can make lots more power and not trim it so high. I wouldn't think a nose cone would help.

[powerplay230]

Hey that sounds like great performance from that hull and a small block!
When I looked at the Baja's a few years ago I was pretty much told they are not built to run that fast. Being their starting model that is cool I think I was told they are made to run 60- to upper mid 60s. I could be wrong just what I was told by Thunder Marine down here, maybe part of the pitch to sell me the 25' Outlaw that was stretching my budget t the time.
Hoping you don't mind a question if I don't get flamed :D here, is that on the bottle if so how much difference did that make.
don't take anything wrong cool looking boat and sounds like it already runs great!
Rick

[PLACECRAFT20]

the boat will run a honest 70 to 72 on the motor. with the nos we have got to 76.2 before the chine walk scared us to death. i think to go any faster we need lifeline jackets and helments. anyway it looks like the prop we settled with is a 27 pitch 3 blade. the propeller guy did the blue print thing to it also. i think we are turnig about 5600 without the juce. and to answer the last question, it is not a stepped hull. when duke got the boat it ran 59 to 60 on the gps. it came with a 305 fuel injected magnum if anybody needs a new motor. it only has about 5hrs on it.