H&R's on the front only?
 

Okay, here's my dilema.

I'm gonna be putting 18's on my car real soon but it will look hella nasty with the back being lower than the front. (Why does the stock suspension sag like this?) I want to maintain an as close to stock ride as possible though. So what if I lower the front only? Will this totally throw off the balance because the front will be stiffer than the rear? Has anyone else done this. My friend is going to do this on his bimmer as well but we are both unsure. What are your thoughts?

not a good idea
 

you'd want the rear to be stiffer to, or else you're going to be driving and pitching when accelerating and braking (which in terms of physics, is still accelerating). I'm assuming you'll scrape a little more in the front since the front wheels will serve as fulcrum with shorter springs in the front. I have H&R's on my 97 and it's fine. Sometimes it looks like the rear is lower, but with the lip it's perfect. Also when you sit in the driver's seat, it evens out.

It is an illusion. The front is actually lower than the back with the H&R it is just the Nissan design of the front wheel well. Get the H&R for sure put all four on and you will be happy! With some nice 18"s it is going to look sweet!