Hi,

thought i'd better post in here too,
this is my other thread on the legacy BH5 TT to ST conversion:
viewtopic.php?f=10&t=21729

I have also done a legacy BG5a TT to single turbo using a stock v3/4 WRX 1s ECU (JDM WRX ECU that runs yellows, orange AFM & VF22, 6S ECUs are the proper STI ECUs), BG5a's are 4 plugs at the ECU, so a full repin is required to turn it into a v3/4 three plug WRX set up.. well worth it!
Later model BG Legacy GT-B's have 3 plugs at the ECU and are much easier than the earlier BG legacy's.
ReubenH has a well know thread called "the single turbo thread" at clubsub.org.nz, that covers the mechanical side of the conversion and wiring for the three plug BG legacy to v3/4.
NOTE: the 4 plug BG TT to ST is not as widely covered/documented as the later model 3 plug legacy's, coz in short its a be-atch! (but can be done)

I have the pin outs for a 4 plug BG5a and a 3 plug v3/4 WRX, plus A3 wiring diagrams for a WRX v3/4 (no wiring diagram for BG5a just pin outs only)
here: http://cid-cfa30f34a9604d4a.skydrive.li ... 604D4A!161