Currently running a short XR with sport master case. Turns a Bravo 34"lab at 6000 on a 1.5 gear (117 radar). Prop runs deep with the full bulb in the water at top end. The boat is a 25 ft Warlock cat- heavy. Close to ventilating the prop just as she comes onto plane. Thought about a IMCO with a 3" rise or the Stelling with the adjustment. WIth that - the boat went on a 200lb diet in the stern and added another 75hp over this winter. Thoughts go with a 5blade to deal with the venitilation issue. This boat likes good chop- severe porpois at 90-100 in smooooth water- one of the reasons for the diet- balance.
Ins and outs of the standoffs on this size cat??

They look cool.......that is a bonus right there!

my 27 ft v hull hated the stellings box,Smitty

Did you change to the Stelling only or make other changes? What did the boat do after your installation??
I know the two boats can't be compared- but do you still have the box??

I installed the box in the plus 1" position because of my "suppposed" conservative 7 1/2 in prop c/l depth. Boat lost 3 mph,porpoised,blew out prop,wouldn't carry bow,had amplified tq steer. Tried numerous props including 5 blades. Boat acted like x-dim was really high,added a 1" spacer,it got rid of 80% of the problems box created but lost a additional 3 mph,gave up and pulled it off and sold it a month or 2 ago. It looked cool though ,glad I didn't glass in and remove the transom mounts for my twin rams,Smitty

There is likely more you will have to do than bolt on an standoff box. For one, you are moving the CG back as you are now hanging the drive back an additional 12". In my boat, this meant the inter strakes had to be lengthen. The extension box is no different than any other aftermarket part, they generally work in combination with other parts or modifications to achieve the maximum potential.

You can't compare a v bottom to a 25 mod tunnel. I owned a 25 SXT and ran a stearn power drive which runs a # 3 small
shaft cleaver wheel.
I found with this set up ran faster than any bravo set up with
the engine on the trans.
I ran a plug in transmission and the prop was 10" further back than a bravo.
I think the trick was having the engine forward correcting some of the CG issues.
The hull was built with a longer engine compartment to clear
trans & blower pulleys.