5 Psi on a T-25 has been done many times without an IC. To keep cost down you could do it but I still think it would be better for the engine if you had one with.
Also, the tranny cooler is a good idea but you wouldn;t really need it unless you were on a track or on a passing spree on a highway. The turbo only puts more strain than stock when in boost so the tranny would only heat up more than stock in this case. Good idea though. Later...Brian