alpha gen 2 and horse power
 

I have a scarab 29 with twin 350 mags, and alpha 1 gen 2 drives. I was wanting to do some upgrades with small blowers. and was told the drives would not handle the extra power. If anyone knows how mutch hp these drives can take?
I would like to know. my local boat dealers seem unwilling to help with these mods.

approx. 325-350 hp

Be happy the boat does 65 and go have fun! If you want to bump up the motors get bravo drives and transoms! Ask your dealer to sell them for you. There is a market for your drives and transoms but you will have to dump a boatload of money to re rig everything. Have the same one and considered it for a minute then logic kicked in.

I've seen guys run 330HP big blocks in front of Alpha's. I've personally run 400Hp thru one in a 24 P&D for over 3 seasons in Lake Erie with no problems. As long as you are easy coming out of the hole and don't fly the thing like a mad man you should be able to put 400-425Hp from a small block thru them with very little trouble. Maintenance is keyand run good drive oil.

how mutch hp do 350 mags make?

A 350 Mag makes 300 horses.

I would be happy if the boat did 65 at my local lake, of 5000 feet. It will do 65 at lake mead. But that is a 7hr drive.
At 5000 ft it falls of to 59, and that seems a bit slow to me.
any tips on getting it to run 65 at 5000 ft ?

YES.

Boat size matters too. With a smaller boat, the alpha could handle 400hp but you have a big heavy boat which is tough on those little drives.