First of all, where is it in the IS? 2nd, I have a greddy (blue one) emanagement system. (piggy back I believe) But I would like to know if I hook that up, what could i do (as of air, fuel, ect...) and how much performance could I see?

 

are you hooking that up to a stock IS?? what's the point

 

Right now I have a 100 shot of nitrous going to it, but I have a T3/T4 setup that is about to be installed. Would a aftermarket ECU make a difference to a N/A IS300?

 

the gains youde get from hooking it up to a "stock" is300 wouldnt be worth it but when you get the t3/t4 fuel management always helps. If you find the right ppl to do it of course lol

 

Under the hood, drivers side. It's under the cover that looks like a big fuse box cover. It has a vent hose going to it.