[DKX4///M]

I plan on running these with dual boost activated 3" exhaust dumps (with turndowns) before the secondary cats, along with a electronic boost solenoid...

(I've had exhaust valves on both turbo cars Ive owned, My 2003 Evolution 8, full bolt ons, HKS Camshafts, and Evo 10.5 hot side, and meth injection...) Open vs Closed, just tuned to avoid boost spikes and the reduced IAT's from the reduced heat of the turbo added almost 30whp...

While I never got to dyno my M2, and I never got to tune it to take advantage of the reduced heat and back pressure, along with the less restrictive stock exhaust I expect much less than 30awhp, like the EVO...

I also ran either QTEC Electronic valve dumps, or boost activated dumps on all the shop full race and customer cars that were turbo charged and looking for the most power possible...With night and day results vs similar setups running even full2.5" or 2.75" straight pipes...


But on an X4M running very high boost, I suspect exhaust dumps placed properly and tuned to take advantage will add a noticeable amount of power, and an obnoxious sound which some will love and some will hate.

But also the advantage of a very reserved sound when closed, no more tickets, no more pissing off neighbors, and absolute lowest lag time, with absolute peak possible HP from exhaust flow (when openeed) ...At 1/10th the price of most quality after market exhausts...

Just something you may want to think about, obviously not for everyone...