i machined a cross brace then realized it was a waste of time and simply weldon cemented 2 strips of PETG at .18 x .25 x 1.25 overlapping by .25 then slotted the cowl on the CL and cemented them in place. Then I sand off the brace even withthe cowl OD, chick iit in the lathe and center drill the support rod c'bore. done! I use a .1875 ball endmill to cut 4 opposing slots belowthe midline of the cowl followed by 8, 12, 0r 16 .25 dia. drilled holes between the slots (more holes = more flow so you can limit flow a but or go all out). The retaining quick turn disconnect that fixes the cowl to the Maxi body is .180 deep and .080 wide to accomodate a snug twist fit on the maxi. The rest is a .25 OD 316 SS tube x 1.25 lg. press fit on the impeller shaft (impeller blade removed and tab sanded smooth). impeller body is drilled out to .128 for clearance of a .125 dia. 316 SS shaft with the original Maxi shaft bushing drilled to .125 and pushed on. I have to agree and disagree regarding the suction cup issue. I make acrylic mounts of .25 x 3 x 3 with 4 c'bored cup retainers that hold like glue yet allow easy adjustment. 3 cups doesn't work, 4 does, looks good, and isn't bulky like mag holders. I use a modded penguin 1140 and a MJ-900 in my 120 and get all the flow I need. when you point them at each other the currents collide in the center and generate a randon flow that the corals love and the fish have no issue swimming thru. It's all goos and doesn't cost $300 a pop. There are drawbacks. Noise, heat, bulk, and the inherent random reverse restart issue. The acrylic mounts host coraline fairly quickly too but that's never bothered me.
My next mod is a Mag 5. I've been looking for jus tthe right prop cuz the Trolling morot one I got form Ebay has a hub dia. that's too big. The mag 5 mod would be killer in big prop systems and tanke over 300 gal. We;re talking about 2,500-3,000 GPH in the flow pattern the Maxi mods have... Grunt Grunt!