beleive me when the cat is not bashed out and all that shit is still in there you can tell your gtr wants to go but it just doesnt, also makes the exhaust sound abit different(more rb sound) well im just telling you how my car was with it and how it was after i changed exhaust, mate all you need is an pfc and a decent tune and beleive me thats pretty much the bolt on mods done but also make sure you change ur cam gears, lol mate when you change them it will feel like the hks r34 gtr(ultimate response lol), just trust me and go do them and you wont regret it, they are mods that i got and mate i love it, not sick of the power, ok some people have more power but beleive me where you are now and where your gona be afetr those mods is a complete difference mate and will be a diff car, you say your getting exhaust done as we speak, that will cost you a fair bit but if its full from turbo back,
apexi pfc- 1k
cam gears etc. greddy,hks,tomei will cost you $380-$480 delievered
timing belt- $150
and then ofcourse the labour but these at the best mods to do to your gtr from stock,
cheers tony