So I finally got a chance to drive Mirage for a week, and here is my verdict on TEIN Basis coilovers: don't buy them, at least until you read below, and if you can wait, wait until they fix it!
TEIN Basis feel great out of the box on smooth roads, but will act as blown shocks on any reasonable size bump or pothole, which we on East Coast have tons of this time of the year. After a big hit wheel starts dancing, and the whole car gets upset starts oscillate.
Shocks do not have any signs of leaking, and when we installed the coilovers initially the springs looked too soft. The springs are progressive - varied step wind, so they should be soft for initial part of the strok, and not having enough weight to load them we decided they will be o'k once installed. They are for most part, as long as road stays smooth.
So I called TEIN, and found a few things after talking first to tech support and then customer rep.
From tech guy I got this: Mirage coilovers are special order items. This means they are for Japan market and had not been tested/endorsed by TEIN USA. They can warrant it if it is leaking, but in terms of having a bad mismatch (too little resistance on big hits and soft springs) they don't do anything as it is not a product for US market. In other applications US models often have more damping and different springs.
Being upset to the point of going online and badmouthing TEIN, I call again again and talked to customer rap. He basically confirmed what tech said, but was more susceptible to criticism. The fact that Mirage coilovers are listed in US site catalog and there is no clear "use at your own risk" disclaimer This is going to be corrected, they will put an explanation on TEIN USA site.
He advised me to take coilovers off and send them to TEIN for warranty inspection. They will test and see if the parts are within the spec (which I have no reason to doubt) and can actually re-valve them for stiffer settings.
But basically the bottom line is that product has not been designed for US market, and as such they can't guarantee optimal performance. Tech tried to pedal possible difference in weight but 100lbs will not create as much difference, IMHO. Driven in Japan I can attest that the road conditions there are very different, while the surface on some mountain passes may not be the best, there are no potholes to speak of. Snowbelt/NE/Mid-Atlantic is especially bad in terms of huge potholes, but may be not to the same level as Montreal. But at least in Montreal you are going with low speeds in straight line.