ST or Addco? any noticable difference in performance?

iw as thinking about how I could make the car a bit more nimble or even light on its feet....   There has to be a decent amount of weight to be lost in replacing the front K member with a tubular one... and especially the rear one... I know it would all be custom made but I have a guy who could do it no problem and he is not all that expensive ( he builds pro stock cars as well)   I wonder how much weight could be saved     any one have any weight figures for either or both of those frames?

Well i have finally decide that i'm going with MAGNA MPI, i don't know if i can modified the Magna with a 72mm T-body from Ford, with Megasquirt computer system, iguess its lot better i will wait when it comes out the Megasquirt II(2), i'm going to get 3 angle valve job port and polish, with arp head studs, 3 stage ACT clutch, 20-22lbs. flywheel modified from TEP,race cam, Wiseco Pistons, 3 inch EIP down pipe, 3 inch Exhaust, GT-Series Turbo (it makes around 260 to 350HP the turbo it self GT- SE

A 12" subwoofer I'm interested in has a recommended cubic feet volume of 0.8-1.5. Now, my question is, is this number recommended MINIMUM or is it the IDEAL?   By minimum, I mean, as long as the cubic volume doesn't get any smaller than that, it's ok OR, by ideal, I mean, the cubic volume must be within that cubic feet range, no more no less?   Will going beyond that 0.8-1.5 range make the woofer inefficient?   Thanks, MANGO