The Koni's have lifetime warranty but it might only apply to the original purchaser. I would check into that. You might just need the original receipt.
As far as ride being firmer, it depends what spring rates are included. The rates could be close to the springs you have now, but you can get pairs of springs from ground control at whatever rate you want. And of course the damping on the Konis can be adjusted to match whatever spring rates (within reason) you choose.
As far as ride being firmer, it depends what spring rates are included. The rates could be close to the springs you have now, but you can get pairs of springs from ground control at whatever rate you want. And of course the damping on the Konis can be adjusted to match whatever spring rates (within reason) you choose.