your best bet and the route that will reduce the level or migraines to none is buy ones made for the blaster , I have +3+1 long travel a arms , I have seen +5 +2 a arms on a all out race blaster ( schneider brand? ) pretty sick looking plus the 2g's worth of elka triple rate remote rezzy sexiness keeping them smooth as a baby's butt in the woops .
yeah , just spend money dude , its totally satisfying ......
You could get +2 forward if the upper and lower were built for it but (my math is serving my right) you'd be the other side of the bump steer problem but you'd have tons of ackerman from that.