170 & 208 m030 *
180 & 190 h&r *
These are the "soft part" of the progressive springs .. And the ride will also be determinedly the roll bars on the m030 kit
The only way a boxster will/should see anywhere near 500lb is on track-only car
Although the eibach set-up seems more favorable than the h&r for what you want , and can still be bought in Europe,
You should have a serious look at the vogtland lowering springs
Little known German company that have been around for years that often get lumped-in with the "economy" lowering spring crowd as they don't advertise as aggressively as eibachs and h&r
*
I am researching these figures and still don't have a definitive figure. although the info is out there on most aftermarket German equipment due to the TUV laws .
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