I'll provide my opinion on your #3. Performance chips in a gasser are a waste of money. If it's a diesel, that's different. ENORMOUS gains are made by chipping or tuner boxing a diesel.

OOOPSS!! On edit, I just noticed you DO have a diesel!! Yeah, chip it! LOL Though I'm unfamiliar with how Bimmer computers will (or won't), accept the change.

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Cheers!
Chris

03 X5
02 Acura
88 Mustang GT Ragtop
88 Campion Allante 195
99 Itasca 29