Best bang for the buck at least to me means getting the best value and product for the amount you spend, I'll address each point of your seperatly, please keep in mind that this is just how i am looking at it and not detracting from any of the drives mentioned as they are all nice.

ASD, depending on how the boat is built from the manufacturer, the asd drives from what i have read need rocker built in to the hull as they are a true surfacing drive. if your hull and bilge are not set up for this type drive then along with the costs of the drives you will have to do considerable changes to modify the boat to fit, not a bolt on and go application. Rik has posted that the asd only sticks out 4 inches further than another drive on an extension box. I don't have boxes on my boat so the asd is 16 inches further out than my XR's, not conducive to my type of boating. pricing listed on here for new would be between 45-55k for the pair. not including any structural bilge and bottom work to make the drive fit the boat. total gonna be about 70k not including props

Xpower- like the imco, it is relatively a bolt on drive, also like the imco it needs new helmet and gimbal ring, however price is again the issue, 30k per side is for drive only not the gimbal and helmet, although on a couple boats, still not tons of testing or unbiased data to make me want to drop that amount of money. no bottom mods needed for drive so say conservatively 60k to switch not including props

Imco- looking at different people that have the complete drive listed price in 1.5 ratio is around 13.5k, helmet is 900, gimbal ring is about 1k, depending on shaft you can run same prop as before, so 16k per side. comes in -2 standard and if you add in having lowers blueprinted add 4 k total, you are looking at 20k plus spacers if needed, so say 32-35k not including props.

Ther have been a few boats that i have seen and read about with no noticeable speed loss switching to imco scx, one top gun here in MD done by MDG was what convinced me, so to me the numbers lean to IMCO.

Thank you for the explanation.

One thing. What I understand from Rik, is that usually most boats does not need hull mods, that includes notched transoms. Are the issues with rocker something he has talked with you about specificly for your application? I can't help but thinking, a surface drive is a surface drive, the hull does not know what's spinning the prop. So wouldn't the same be the issue with #6, Indy or X-Power drives compared to the ASD#7M and the other ASDs?

You are correct the boat doesnt know, however if the boat was set up with no rocker in order to get water to the surfacing prop at speed. Its the same as guys putting blackhawks on boats with no rocker. i have never spoken with rik on it personally but i have followed his posts intently as i do really like arnesons and would love to have them on a poker run boat one day.

Man guys I have a 27' Daytona with 1100hp easy runs over 130mph with a XR drive and a 1.35 gear and a worked 34" bblades Brave one prop. Love to see what this boat would do with the new drive and a big surface prop!!! Any offers great test boat!!!

I have to ask, what is the aversion to BMax? They have a Poker Run version that has a more hydrodynamic lower unit. I'm just asking because I know I will need to do something myself pretty soon. I got a quote from them last season and I think they were about $15k. If there is something we should know about please tell us. Other than BMax, I'm looking hard at All American Drive Service, they will at least warranty their work.

I remember a pretty long and detailed thread about X drive from a member here who put it on his boat...single engine I believe. Lots of info but most of not positive and X drive support horrible.
Can`t find it now maybe some politics involved and it got removed..

It wasnt on this site, it was on another forum that I read it. I believe it was Kap who tested it and did a big write up on it.

BMax is a great drive, but even the poker run version uses xr lower gears. Yes the gears might be set up better but they still are the weak link. All American Drive sounds good but a warranty is only good as long as the company is in business. Mr Gadagets also builds good drives down in Holland MI.

The main point of this thread is about the SCX-4, which has larger upper and lower gears which are stronger. Its a surface drive which gains speed, and allows more prop choices. The Bmax is not a good comparison to the SCX-4. It is a good Comparison to the regular SCX. In that case the winner would be personal preference.

My opinion, if you don't have issues breaking lower units now then the BMax is the most cost effective choice of all the drives. 1 yr warranty as well and easiest to install since it does not require a bell change. I kept blowing IMCO Extreme SC uppers so the BMax solved that problem for me.

I agree, the -4 isn't a good comparison to the BMax. There are people running the SCX with SC lowers, that's a direct comparison.

There's also documented loss of speed from both drives. I lost only a few mph when I made the swap but that may have been from the gear ratio change and not necessarily the drive. BMax also offers a 1.50 ratio which was unavailable when I purchased my drives.

Other than the previous owner, I don't know either... Perhaps it's looks? The IMCO has the BMax beat in the looks department, I'll admit that but the BMax is a stout drive and has been in the field much longer.

I've been running 838 hp / 834 tq thru these drives in a resin bucket Apache since 2007.