looking at installing boxes. just wondering if they work well add speed, which ones are better for xr drive, and lowest prices and where to buy

That's what I understand......something about better water (less bubbles) for the props. Some boats see 3-5MPH improvement in speed.

What kind of boat? I had some from the factory on a '98 35' single step Fountain and I loved the difference. I don't think you can put them on TS boats because it ventilates the hull to much.

My Formula 382 Fastech (twin-step) came from the factory with Stellings extension boxes and XR drives. No problems with slip or planing. Love the set-up, ride, and handling!

I asked Fountain about putting them on my 38' back in 2002 and they said no way

I have seen a 29' w/boxes and it chine walked like a biotch

Aaahh ... the other "F" boat! You mean a 27' w/boxes chine walked, don't you? Maybe the boys at Formula have something on Reggie after all?!

better take a look at your X dimension and transom angle prior to your purchase....you may need to pull the engines and plug the transom as well.

I saw a Stelling ad for the boxes. I was a little confused after seeing the ad. How does the input shaft to the drive get it's power? Does it slip into a different coupler in the extension, thne have a drive shaft bolted to the flywheel? Or do you put on an extended input shaft that runs thru the extension, a carrier bearing and then into the original coupler?

been there.. and had to move the motors, too

You take off the stock coupler. There is a new steel coupler that is bolted on. The drive shaft bolts to that coupler. The drive shaft is a double knuckle that goes to a center bearing. This bearing is aligned with the gimble assembly. The splined drive shaft slips into the center bearing. Never remove the center bearing or you'll have to totally reallign the assembly.