How much of an improvement is a 353 with boxes over one with out? With my boat in pieces I was kind of thinking that this could be the time to do the upgrade. Not sure if it is worth it for the boating that I do but want to see. Boat has 500HP's in it.

We had an 05 353 525s with ITS. There was an 08 353 525 boat without boxes in our local club. Side by side I was consistently 4-5 mph faster. The real speed difference began to show from 60mph on up. Could there have been other variables? Im sure but when I was shopping 353s I liked the way the boat ran with the boxes vs without. It seemed to carry the hull better with ITS. Also, Im not 100%, but wasnt the X raised around 03 on all 353 production.

Not sure on the raise in the X dimension. I am looking at an IMCO or similar, so that would be farther back then an ITS as well as higher raise? Mine is a 99 and the drives are stock for now. That will likely change after a year or two if I decide to keep the boat.

A friend had an 2002 with factory installed Stelling boxes and 500efi's. It would run right at 82-83 mph with the factory props.
General consensus from what I have seen is boxes add 2-3mph and give a little more bow lift.

Neither imco or merc its raise the drives. They actually effectively lower them if they are neutral boxes

I did some research a few years back on 382's. Boats that came from the factory had a 1" raised x dimension.

The ITS setback is just shy of 8 " a true box is usually around 12".......if not done right they will slow the boat down, need to see where the prop shaft is now.

You sure? I thought that Imco did raise? I know Stelling does have both raise and neutral.

Just saw that if you do the 3" boxes you have to raise the motors. So that is not going to happen. Probably better off just putting the transom assemblies back on and going with different drives.

Jon,

" Nauti Monkey" runs Imco neutral boxes....they actually lowered the drives hence why AXAPowell installed -2" sportmaster lowers. As you know the entire drivetrain of my boat was done by Dave when he owned the boat. The time that he put into configuring the proper setup is well documented in all his threads here on OSO. Personally I suggest if you are going to make changes that you duplicate exactly what I am running. "Apex Warrior" here on OSO (Matt) has a similar setup as mine I believe...you may want to reach out to him as well. Matt is running more HP than I and I know first hand for doing several runs with Matt that his boat sits and runs like mine. Hope this info helps.....GOOD LUCK BUDDY !!!

Chris