I asked Chris almost the exact same question about 2 weeks ago because I just picked up 2 Microgel Radical OS's. I wanted his recommendation for what tension to go with when putting in Cyclone 17g. He suggested at least 54# because the 17g is livelier and maybe even a touch higher if I was planning on adding lead. If you check the Cyclone review, I'm pretty sure Chris used the IG Rad OS for that test and had the tension at 52#, I assume the RPM would go in at a similar tension. He also suggested starting out with lead a 3 and 9 with an equal amount at the top of the grip to maintain the original balance.
Let me know what works for you in terms of adding lead. I've got 2g at each of 3 and 9, and 4g at 12 right now. With an overgrip the balance is 4 HL which is what I like, so I didn't bother putting any weight down by the grip.
Last edited by Tommyj : 01-31-2013 at 02:54 PM.