Can I put a gt1 ecu on straight on my gt3 if I can at all? I had a gt1 a few years ago and remember it having 5 more bhp standard.

is it worth changing ecu for +6hp ?

interesting read

http://www.puntosports.co.uk/forums/showthread.php?66329-Punto-GT-Modifications

put simply no you can't just plug it in.. besides we are talking 6bhp, which is less than 5% of the overall power - you wouldn't even feel it and could pickup more power with a few mods. The ecu in the car is mappable so a decent tuner could remap it and make more that a gt1 does or stick an off the shelf chip in it.