Significant differances in S13, S14, S15 SR20DET?

[Second Shadow]

Okay, though I know I might find the info I need if I look through this forum hard enough, I'm going to pose the question anyway, to save hours upon hours of my time. I know the basic differences between the S13, S14, and S15 SR20DET engines, and I know that stock some perform better than others. But what I want to know is how do the differences in their designs effect the way they perform and how you can use their potential? For example: the s13 (black and red top are the same here if I'm not mistaken) has high port fuel injection giving it a strait flow path, while the S14 and S15 have low port fuel injection, which means a sharp turn somewhere I believe. Does that differnce mean that one has perhaps a better flow from the intake manifold to the cylinders than the other? Also, the later engines have Nissan's varible intake timing. Does this work well in the SR20DET? or is it a problem that breaks alot? or does it work well stock but really becomes insignificant or even a liability when trying to tune? I have a 93' 240SX SE, fastback, with no major powertain modifcations. I'm planning to swap in the SR soon, but I want to make the right choice the first time. This is my daily driver, but I'm into autocross and roadrally, and I like drift sessions as well, but I don't really drag competively. I'd like to start actually placing in these events someday so I've decided to do the swap. 350 hp is about all I'll really ever expect to compete with, but a little more for drag racing would be fun. And since this is still a daily driver and used for autocross and road rally, midrange torque is pretty import too, not just max power. I'm sorry if this question is a little vague, but your imput is really apprtiated. Thanks.