the first (and only other set i've seen in person) set of twins i saw had what looked almost like a subaru turbo on top. i think i've got teeth bigger than that thing was. he put 650 down that day, i think. with a good ex. gate, i think an hx 30 sized turbo might be good
. i'm no expert though. my twins are definitely smaller than most. got the hybrid on top and an ht3E on the bottom. the 3e is a little smaller than a 3b all the way around. smaller turbine, compressor wheel, housings (22cm exhaust housing). spool is ok, but could be better. i haven't driven any other trucks with twins yet though, so it could be quick compared to others. i've got a little something under my sleeve though. my next project, when the time is right, is vgt twins. i've got a smallish 35 or so sized one, and a 55'ish sized one. you want to talk about spool? the small turbo's housing will prolly squeeze down to less than 8 or 9cm, and the big on down to about 17 or 18cm. that'd be some low end, i reckon.
we shall see.
dave