I have had Rolling road data back from a before and arfter with the GT chip and a gain of 6bhp was recoreded with a Decat exhaust and air filter mod.
All the AAV, 3F, PY chips are available for £26 including postage, and the early NZ engine are available for £35 as the eprom they use are very rare as they are no longer manufactured
All chips are supplied with very detaileed fitting instructions and a nice storage box to retain your original eprom. I can also solder eprom sockets into later Mk3 ECU to allow tuning chips to be added.
Anyone interested drop me an email at poloace@aol.com
All funds genereated go towards a worthy cause.... my G40
Cheers
Alan