Well I too pondered the steel vs aluminum expansion ratio, I'm not sure what the answer is but the steel cylinder liners are an example - the top of the stock liner is a light press fit in the case but the lower skirt is a loose fit with the O ring boss just about touching. So the theory is the liner gets hotter than the coolant cooled case area and the area around the skirt below and the liner grows to a snug fit ? I spoke to Ray Vreeland and he said the liners he specs for the 1320 are a tight interference fit at the top and .004 larger on the bottom for a snugger fit than the old Wiseco/Darton sleeve kit and they don't crack pistons or liners with the CP pistons. Having said that the differential temps of the surrounding case and the oil bathed engine brace would have to be considered to really know what the final differential of expansion between the two would be. The directions for the kit has you put red locktite on the case stud end, sequence tighten to 10-15 ft. lbs, install the brace/girdle, apply ARP Ultra Torque on the stud end, and beneath the nut where it contacts the brace. ( NOT between the brace and the stud boss faces ) then sequence torque to 10, 20, 35 and 43 Ft. Lbs. So theoretically yes, the brace and bosses could have some relative movement if the expansion rate is that different ( don't think so ) but 4 ARP studs locktited @ at 43 ft.lbs I doubt much and it won't get loose so in practice so should not be a problem. At 2 lbs I think the Trask girdle is a vibration damper/ pendulum weight as well and like the other brace/girdles may help to defoam the oil returning from the crank area to the sump. They work - ask the 200+ Hp guys. Roddy how does the HolyMoto brace tie into the oil sump/case bolts ? Do you have to use their sump that has reliefs machined into it ? Can't find a good view of their brace you got one ? :blahblah: