I'm looking to increase the HP on my twin 2005 Merc. 6.2 MPI. The engines put out 320 HP at the prop now, I'd like to get the HP up to 375 to 400 HP the most economical and reliable way possible. Any recommendations for an easy fix, is there a chip that increases HP, etc.? Thanks.

6.2 your best bet is to pull them out and replace with big blocks, 6.2's are pretty maxed at 320hp.

Get a new engine.

Agreed. Going from 320hp perside to 400hp is only good for about 4-5mph.

Bingo...don't waste your money or time.

trade it in on something with blue motors

You would need to replace the intake manifold to get any power increase. The stock intake just doesn't flow enough air to support any HP increase. With a a carb or aftermarket efi, cam change and some head work you can get 400 HP. Beyond that, change engines or leave it alone.

whipple charger mite work

Those were my initial thoughts too, I'll probably keep the boat for another season then look for something new in the winter months. Thanks for the responses.

I remember Uncle Toys tribulations with those on his 6.2...what a saga that was.