I have to 60 moto's......they leave lots of growing room!! .....
go to check out turbotweak.com...... I got mine there, eric's great to deal with...very fast!
I have 42s and they work great. I understand everyone's logic to go with the 60s and have more room to grow with other mods, just depends on your budget and how fast you want the car to be in the near future.