Definitely not. I got the FMS B springs (similiar to the wimpy pro-kits), and I definitely want more rate.
Just make sure you do the shocks & struts at the same time.
www.oemfordparts.com and
www.buyfordmotorsport had the 2000 cobra R bilstein struts for half the price of anyone else! $275 I think. They'll handle the heavy spring rate, and supposedly offer an excellent ride.
www.shox.com has the bilstein rear B46-2148 shocks for $70 each. SO that's $415 for awesome shocks & struts... then you just need some springs. You can get teh sportlines for 189, total = $604 + shipping.
The FMS____R58 springs were used on the 95 cobra R, and they're actually the Eibach R springs (700-850# fronts, 200-260# rears?). They're a pretty good price too.
If you went a little lighter (FMS-C, Eibach sportline, H&R supersport), you could use the tokico illumina's, which are a little cheaper (they won't hold up the same though).
www.shox.com also had a Tokico Illumina Suspension Kit $579.00. The sportline 660/260 should work alright with the vert. I'd pay a little more for the bil's though.
Koni makes a great shock, but they'll be a little rougher on the road (unless you pay for the DA's).