I'm running a 10" travel Fox on my RTE 3" set-up and it seems about perfect. I know if you talk to RTE they will tell you to get a 10" also. I run limit straps in the front and cones in the rear, on full extension the rear spring moves about halfway down the cone so you could probably run a 12" if you wanted to, provided the shock body isn't much longer, you don't want to bottom out on the body it will kill your shocks, also don't forget to buy longer bumpstops, you'll be glad you did. My shocks are the 2.0 w/ remotes valved at 85/95 on all 4 corners. However I will say that on a slow trail with lots of flexing there is no performance gain between my $190 Foxs and my budies $30 Pro Comps, they're only worth it at high speed, I can outrun a lot of 200-1000 class buggies and put my freinds Rangie with the Pro Comps to shame, because the Foxs just don't fade. If you do't plan on taking it to the desert races or Baja, save your mony and just get some Ranchos or ProComps.
