Are you planning on getting custom pistons to lower the C/R or not? if not, twin turbo is pointless with the low(ish) amounts of boost the engine can handle before your ring lands on cyl #5 will (yes, I said will) meet their demise.
If you are going with custom pistons, then forget I said anything and good luck.
It is possible to do a twin turbo i/c setup in the engine bay if you remove the ABS and relocate the battery, just a bit tricky
