the CT's maybe physically larger than the 20G, but will not flow more air... 20G's have put DSM's into the 10's and 11's and well over 118mph traps... has a stock CT26/20 put any MR2 into the 10's or even the 11's?

those 3S's have side feed injectors right? you could look into some MKIV 550's and then have all the fuel you need, just add a Walbro pump. if you dont already have one.

what is your intended use for the MR2? a quick daily driver, or a quick weekend driver, or a track only? depending on what you want to do, a Water/Air IC would be most efficient. that DSM sidemount you have is a perfect candidate. just have a welder enclose the front and back of the core w/ some 2.5" inlets on it, then run water INSIDE the core, and blow the charge air over the face of the core.

otherwise, a decent sized intercooler, like maybe a custom spearco core w/ some alky injection would be a very good setup.

i have a friend who could do the pipes for you if hes not busy, but hes not exactly cheap... i dont know what your budget is though.

if you had an EBC that would let you do speed/gear limited boost levels, you could make your open-diff tranny go a Long way... as long as you dont bang the gears like a gorilla trying to make it go faster and end up bending/breaking the shift forks.