I have street bilsteins on the front of my 65.  They are nice compliments for my 50 year old GT springs.  They have nice dampening and there is no harshness.  I only cruise this car, and I like the smooth ride.  620 springs are somewhat stiff for my taste, and I have no experience with 620's & bilsteins.

 

Last edited by TimC (3/23/2016 2:04 PM)

Shaun over at Street or Track sells Bilsteins that he says are specially valved for our cars.  That's what I bought but my car hasn't been put back on the street yet so I can't comment on them.  My own personal philosophy on street shocks and springs is bias low on the spring rate and bias high on the shock valving.  I had KYBs and 600 psi springs but the car was too still for me.  I would also look at doing things to free up the suspension so it has to overcome as little resistance as possible in order to do its work:  using bearings to replace rubber in spring perches, the idler arm, and delrin, UHMW or similar high impact plastic in the leaf springs.

DBrown,
I will trade you my new 200 mile Bilstein street shocks for a set of Bilstein sport. Street ride is firm and good, I just like throwing my mustang into the corners a little more than some others and would like to upgrade to the next level.
Thanks