Like many have said, a genuine nissan service will give you a good logbook, but you'll pay thru the nose. There are some great 'tuner' based mechanics around, such as Boostworx and Tillbrooks, however for my money I go to Road n Track (Gil Camerons workshop), as I've been with them for a long time and they've never let me down... theyre close to me (tillbrooks is closer) but I've had nothing but top service from the guys at road n track. Theyve done a lot of street machines, sprint cars, exotics and their fair share of imports too... the guys who work there are really into the job, most of them race either sprint cars or targa tassie, couple guys do the adelaide classic.... if any of u guys have heard of charlie kovacs, his car was built by these guys..
Going back there in a month to get a stupid amount of stuff fitted. ECU, cam gears, gauges, clutch, gearbox, fuel lines. It wont be cheap, but it'll be cheaper than some, and Im really happy with the tunes that Ive gotten there. Check my sig
-D