Just installed twin 454's Gen 6 on our Wellcraft Nova that was recently purchased , bravo 1 drives ,bravo 1 props 4-blade.
we were at around 60 mph and i went WOT,after 3 seconds boat made this sudden right turn (pretty scary) one of my friends ended up on the floor ,well we kept cruising for about 30 min at around 45 mph and no problem, then went wot again and same problem,we definetely have a problem and need to find out what it is before i take my family out on this boat.Did anyone has this issue before?please help,

Did the starboard engine rev up during this turn? Just thinking the prop may have broke loose from its grip (ventilation) creating drag on the right side, with the port still pushing.

Youe cruise just fine, correct? How about getting on plane? Any issues there?

Tie bars? Hydraulic or stock steering?

I am curious if you spun a hub on the one side. Under low strain it would function but under wot it could give. Long story short I had this happen on a triple log pontoon n had to go to a solid hub because we were grenading the composit.

This may be a stupid question but are the drives setup for counter rotation?

Ken,

prop hubs are new, cruising after that fine at even 50mph and gets on plane in no time.Did not hear engine reving up at all.I spoke to a friend and told me that drives might not be aligned correctly.
any other thoughts?

Just because they are new doesn't mean one couldn't have gave way would be worth pulling prop to see.

But if it did not rev up then may to be that.

Tie bar -yes
steering -stock

If i grab one of the drives (out of the water) and move it left to right back and forth there is a bit of play there but i think a bit is normal isn't it?

They are counter rotating drives ,and are rotating out .