What is the significant difference between the two?

Anyone have good/bad experiences with either?

Which one is better suited for 650 HP on a 28' 5800# V Hull?

Thank you!

The IMCO extreme SC has water jacketed cooling and uses Mercury XR gears the top cap is held in place with 8 bolts as compared to 4.

You should call Dave at IMCO he will tell you the truth, I was going to buy a Teague XR and after the conversation I had with Dave and Teague.

You definitely get more bang for your buck. I run about 730HP and finally have a piece of mind when i hit the throttle for under 9K.

Nice drive

Its not the Extreme SC, just the Extreme.

I'll try to call them, but was looking for actual user reviews, I'm sure I know what they'll tell me.

I've had friends use the Extreme and were happy. I used the XZ and if I had another boat with them I would rip them off as fast as I could. I wouldn't even need tools. My XZ's used with 500efi mercs gave me so much misery. I even had Mec Racing at Lake X go through them and beef them up with XR lowers/towers etc. After a 6 hour idle back to Lauderdale from Bimini I had them pulled, trash canned and replaced with XR's. The XZ should all be trash canned. My opinion only here. . .

Interesting comments on the XZ's. Several of us around here run XZ's on twin cats, high X's with blower motors and have had few issues. A couple of guys have 2 seasons on XZ's.....with no breakage. No putting around either, we run them HARD. Most of the problems I've heard of around hrer involve XR's and wear on the pinion gear. I think Merc had a bad run and have fixed that problem though.

I ran an xz with imco lower on my 25 daytona for 2 seasons, about 70 hrs (the cat gets where it's going fast). Changed fluids every 10 hrs, never an issue with 454mag and whipple at 650hp.

It is the exact same drive as the XR except for the gearsets. I pulled the top cap every time I changed oil and the gears showed no sign of wear etc. It comes down to money. you can freshen an xz and spend on a XR gearset and you now have an XR. There may be more to be had just by blueprinting the clearances upon assy.