Unless you just want a drop that big.. The sr lowering springs on am are excellent they give 1.5" all the way around and are cheaper than them two sets... I just put them on about a week ago slosix also has them to
Think twice about that 2.5 if youve never had a car that low. Sometimes it sounds and looks great but can be a real PITA. Ive owned a vehice (for 18yrs) that layed frame when lowered and it was awesome but without the Hydraulics it would have been a nightmare.
If you do drop.it that low prepare for a sore rear lol...youll also need new shocks/struts, x2 balljoints, bumbsteer kit, c&c plates.... recommend you look for a 1.5" drop...as for them being GT springs youll never drop the exact same but the difference isnt noticable. I run GT springs on mine by sr performance