33infinity33 wrote:Tein's are good springs, if not the best. However, there was a huge run of counterfit Tein's on the market, mostly on Ebay for cheap. These gave the real thing a bad name. I'd bet your friends springs are counterfit. The S-Tech does a nice 1.2"F/.9"R drop. What I don't like a bout Eibach's is they always drop the rear too much, You'll notice on a stock G35 that there is more fender gap in the front than the rear - you need more front drop in lowering springs to compensate for this, like the Tein's do.
A good spring does not drop a car according to how it looks. A good spring has to consider how it changes the dynamics of the car. It's easy enough to design a spring to drop it a certain height. It's harder to do so when you want a specific rate and want to ensure a good ride, good performance and adequate suspension travel. Most lowering springs use very little spring preload to ease installation (if you've ever tried to squeeze a factory spring back onto a shock or strut, you'll know that the springs tend to be exceptionally long and may require a professional spring compressor). Arbitrarily reducing ride height here could make it difficult to obtain the spring rate you want for the given ride height.
And I highly doubt that Tein makes the best springs. Last I checked, they don't cater to F1, NASCAR or any huge budget racing bodies. I haven't heard of any OE's contracting Tein to make their springs either. Frankly, I'd be surprised if they actually use a cold wound spring. Tein has done a good job of bringing function and form to the market. But I would not list them at the top of the quality list, particularly in the case of the springs. If I were to get a set of Tein coilovers, I'd be looking to swap out the springs for some Eibach ERS springs (if the sizes are even compatible).