Im not bothered about the price (as there all about the same ish) as long as they do a good job, good quality.....but if the cheaper ones are better....ill go for them.....my warrenty WILL be intact even if i dont get the x-power springs....
Not sure about the other makes Bri but the Avo's are a 35mm drop and cost me £110. I then paid £80 for fitting at a car modding garage near mine.
I know that the eibach ones are also a 35mm drop and i think they cost about £155. The Xpower ones are a 20mm drop but i'm not to sure of the price (around £170 i think). These were the only ones that were available for the zr when i got mine! And be warned my mate was told that he could have rover 200/25 springs (untrue) so he got the SPAX ones after being told it was a 35mm drop, only to find it sat about 10mm lower!!!
With regards to the warrenty; officially unless they are mgrover parts or you have an agreement with your dealer (like AndyK160- they said as long as they fitted them they would honour his warrenty) your warrenty will be void. But i was told by my dealer (who i have to say are very good) that they would have to prove that any other problems that (may) occur definately were caused by alterations that i had made rather than me proving they weren't! I kept hearing funny noises from the right hand rear spring a few months back so i took it to my dealer to see what it was (thinkin if it were the springs i'd take it back to the people who did em) and my dealer fixed it there and then, no charge!! So really its at their discretion.
My dealer is sound....and will let me do ANY mod to my zed and says my warrenty will be intact....when it was in the last time...i had the zorst, filter, rear lights.....they are well cool about modding!
SPAX now do a seperate ZR fitment...as well as the R25 fitment...!
Your wheels will need re alligning aswell. When you lower a car the top of the whhel leans in. Get this re alligned and it'll handle much better as more of the tyre will be in contact with the road when you corner.