d jetro is only for race cars. stick with afm's. with afms, it will work out cheaper and easier to tune (if the mech knows what he is doin) if u wanna know more about power fc, read this,
http://paulr33.skylinesaustralia.com/docs/...powerfc-faq.htm
open up the exhaust with some dumps pipes. have a look at the trust 1s. their massive and come with the front pipe as a kit with all the stuff u need. (apart from gasket cement.) and the turbos and motor dont need to come out of the car to fit dumps, but it is a mongrel of a job.
if i were u, i would take the car to a well known mech that knows a lot about GTR's and talk to them about it. get it dynoed and see how its running. see what they suggest for power upgrades.
Cheers, Ron