So there you have it guys, a -2" shorty lower unit seems to be the ticket on the 1999 and earlier pad vee Heats.
Keep us posted with your progress.
We are working on Mayor McCheese's (aka Butch Fletcher) Heat's engine now.
We'll let you know how it goes.
Regards,
Steve

I would be interested in knowing the improvement in the MPH. Better handling is great, but picking up a couple MPH makes the investment that much sweeter.

I hear you, but there are variables............
That's going to depend on on your horsepower and current speed. With a stock motor, I don't think it's a cost effective mod. Most of the 502 MAG motors and boats are running 65ish, and they seem to have good lift and acelleration.
The factory set them up properly for the HP and propeller technology that was common then.
With a 550+ motor, it should help. It's like a nose cone. If your not running 80+, there's no need to fool with it, because the stock lower is fine to that speed. However, it does become more efficient, the faster you go. The same with a shorty. In other words at 65, don't bother. At 75, maybe, depends on how the boat is handling. Porpoising is a symptom, as is chine walking. At 80+, yes..........
We have messed with Butch's motor so much I can't really give you a back to back (stock lower to IMCO -2" lower) comparison on MPH. As far as handling goes, the porpoising is pretty much gone, it doesn't chine walk over 80, planes off like it did with the stock lower, and still has good lift.
BTW, that's with stock cable power steering. With full or partial hydraulic, it would be even better.
Maybe one of the guys on this thread can tell you how theirs compared on MPH.
Regards,
Steve

I am still messing around with different props and stuff with my shorty It really helps with the porpoising and such.I have yet to see a good gain with the merc shorty but it got hot and humid as soon as i put the shorty on.Powerquest is my brother in law we both have older non step pad bottom heats, and we both have shorty's