I installed the MPP comfort non-adjustable coilovers this weekend. I've driven on them a couple days now.
In the "MPP comfort coilover reviews" thread I kept reading "firmer, but smoother than stock," which didn't really make sense to me, but I think that is the most accurate description. They feel firm like a European OEM sport suspension. Firm, but not harsh. Driving over BIG undulations like railroad crossings and drainage dips, the car is much more controlled than with the Teins adjusted to medium soft. Less wallowing around, no floatiness whatsoever, and well controlled. Also NO CLUNKING. The Teins always had an ugly clunking noise over certain *really awful* road imperfections that sounded like the shock topping out (hitting the maximum extension). I think the improvement in "smoothness" and control comes from the quality of the KW shock. I think the MPP spring rates are very similar to stock, which is still firmer than I would like.
Without a question, the MPP coilovers improve handling significantly, which wasn't at all my goal, but it is fun! By comparison, when I got the Teins adjusted to my ride quality preference (meduim soft), handling went a little sloppy. I was fine with that, and it was expected.
So which is better? I guess it's a matter of preference. I think I'm happier with the MPP coilovers, but I got them used. At full price, I might be feeling some buyer's remorse from a purely ride comfort standpoint. If you're looking for a handling upgrade, that's a different story. The benefit of the MPP comes from a truly matched spring rate with a high quality shock. But I kind of feel like a product marketed as "comfort" should go a little softer or perhaps dual/variable rate spring (MPP springs are linear like stock). I still think the Tein EnduraPro Plus are a very good value and do offer an appreciable improvement over the stock shocks.
This whole experience has me thinking the Flex Z coilovers might be the ticket for a matched spring/shock at a better price than new MPP comfort coilovers. I have heard anecdotally that they are a little softer, and the shocks are adjustable too. I don't think Tein shock quality is on par with KW, but both are much better than stock.