Just installed my Intrax, I like the ride, but I feel safer with a solid ride, but it won't rattle your teeth, I got my springs from summit, price 209.44, here is the part number from my summit receipt==INT-25-1-040==you will probably need to call them, I had to.
I opted to replace struts at the same time because it was easier, got my struts from
KYB's, price 250.00 for all 4, good luck with your decision, I love the look and the ride!