Long time watcher, first post - be kind. Own a '18 340i M-Sport with BMW sound/exhaust kit. I am looking for ECM flash or plug/play performance options, etc. So many choices, do not know where to start or what is legit. Dinan, ECS, Vivid, Racechip, etc. If you had a $1500ish to spend on engine performance mods with increased hp as objective, what brand would you recommend - or avoid? A huge thank you for any feedback.
BMW does make a kit called the power and sound kit which will get you 35hp and 39 ft lbs of torque. Other tunes can get you more but beware BMW is looking for these mods on the cars and voiding DME and engine warranties from the mods. So make sure you get one that won't modify DME software. Dinan uses a system called a piggy back that modifies signal from sensors to the DME and leaves no trace of its function. More and more tuners are going to this system.