I run the ESS tune and Just got off the phone with them concerning upgrading intercooler and intake and downpipes. They don't sell any of this for the 1M as of now but do recommend going the intercooler way first. Seems an aftermarket intake isn't as good as the stock one for maintaining cooler intake temps at low speeds and its design is much like a c.a.i anyhow. An otherwise stock !m running their flash makes around 350 rwhp or around 400 at the crank.The intercooler will bring from 10-15 same for downpipes. The remaining part of the exhaust is none restrictive and won't bring much power wise. The program will adapt for fuel changes between 91 and whatever upwards octane.As it will also adapt to an intake system and an intercooler without needing a new remap . If downpipes are installed , then a new map should be uploaded via The flash device . I guess they would email the map just like in the initial setup wherein you plug the device,it reads your car info,you send it back to ESS and they send back the modified map for upload. Pardon my french Canadian influenced phrasing..
re-edit.....on the drivability standpoint, it's very impressive and just the reflash on its own pulls very hard......very.