between the eibach prokit and tein S-techs for the 03-06 coupes overall as in comfort, aggresive stance, etc. ?

 

comfort and stance goes to the eibachs as they are lower and progressive. The 350z s-techs take it for performance though

 

the only downside to eibachs, from what ive read...not from personal experience, is that they sag more and more over time.

 

I never recommended them and I personally would never use them, I just answered their question. I've heard about the sagging issue also, but I think thats the case in general for soft progressive springs

 

It depends on what you want. Ride or performance?

 

I have seen both the eibach prokit and 350Z S-Tech (drops lower and has a higher spring rate than the G S-Tech) set-ups. They both looking excellent and afford an excellent drop. They will both lower a Coupe some 1" to 1-1/4". Both will require camber kit(s), due to the increased negative camber. They will potentially promote premature tire wear, if that is a concern. I would personally go with the Z S-Techs.

I do not have info on the eibach prokit. The Z S-Tech has a spring of 386f/403r, which should offer a good ride depending on what you are riding on at the present time. To give a comparison, the Tein Basic spring rates are 504f/504r . . . And they are quite comfortable in themselves.