-ok the pictures tell me its the orginal cylinder on that ski. it has a limited spec factory b-pipe with a twist girdle head. the twist girdle head was made by msd back in the day.
48s are a bit harder to tune but when tuned right will give you alot of torque. Its stands to reason that the 38s will require smaller jets as the engine is bigger and the air speed in the 38s is higher then the 701 engine they came off. Thats the old r&d intake manifold on there and thats why it didnt go as well as it could of with the 48s, did the 48s have a purple top on them. If so it was buckshots and should be placed in a bin hahaha. they were good in there day but that was a long time ago.
Efr borgwarner turbos are just new out (2011) and have been totally redesigned for a performance car application, i suggest you look at this. f1 cars had turbos banned in 1989 thats 22 years ago, there has been alot of development since that time.
Go here and you will see the efr turbos and there specs. I suggest you get John to have a good look at it
A stroker will have more torque I agree but if your spending 10 on an exhaust manifold I am at a loss why you wouldnt use the benefit of the v-cam as well as the stroker. you can also use a more aggressive camshaft and get more up top than you could by using the camshafts you have now. variable cam timing is about giving you the best of both worlds. You could buy a blank of hks and get your specs ground on to the cam.