I bought a 950 that already had the Q4's on them. I think the LV EVOII are much better quality- with fit & finish & performance comparable to Akro. I've run LV for several years on two different bikes, no issues, and they are still in great shape. FMF is a good product with out doubt, and if you want a FS approved spark arrestor- they Q4 has the screens, LV doesnt. If the price on the FMF were $100 less- I would lean in that direction, but at equal price the decision would lean towards LV based on the quality standard alone. Performance and Sound are similar.
KTM: 06 KTM950S & 10 KTM450EXC