Hello there chum; my answers will show egregious ignorance on my part, so prepare to be underwhelmed.
HEADERS - I went to Litchfield Performance in the UK and delegated the solution to them, as I trust them with my life. They also developed the exhausted for and with Miltek - it's the fun system; about £2k GBP for the full system.
SOUND - The sound is DELICIOUS - not aggressively unkind on the outside or inside, but when I clutch in to rev in a tunnel a little bit of wee wee comes out of me, and full-boobies to the 6.1k redline is delicious. It also burbles and even pops on a deceleration.
DRONE - not a hint of it.
CONTROLLER - yes. I had mine mapped to the standard OEM mode so the valves are OEM standard sound in tour, then it gets all Milltek-sexy in sport or track, AND it has a tiny bluetooth remote to open or close values in ANUY mode to over-ride. It's truly the cheapest, most satisfying mod I know of, and I am no certain it has a surprising wee performance boost as I had a head to he'd with a friend's first edition V6 three weeks ago too, and the difference was palpable.
CEL - I'm sorry to be dim but I am new to the teckkie stuff and am embarrassed to not know what a CEL is - enlighten me please and thank you.
