I totally forgot about the SPL aluminum monoball for that bushing. It might actually be fine for that one particular spot, and even beneficial to have a solid bushing there since the whole point is locking out HICAS. I might have to try that out myself at some point, I think the amount of additional NVH would be very low or even non-existent since its just attached to the HICAS delete/toe rods and not taking much shock. I was worried about installing my adjustable powertrix toe-rods since it uses a solid bushing where it attaches to the HICAS delete brackets. It is the only solid bushing on my car and so far its been fine, which is why I think a solid bushing on the knuckle side may also not be a problem.
For whatever its worth, I've been totally happy with the whiteline poly bushings. Make sure to use a shit ton of moly grease on install if you go that route, the mobil 1 xhp 222 special has kept my poly bushings completely squeak free for several years now.
