My cousin is looking to tune his GTS.

Who do you guys recommend?

Does anyone offer a tune that can be done with a cable vs shipping out the ECU?

Thanks

 

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I've been cruising this forum for a while and haven't seen what you're requesting - but you might tell your Cousin to inquire with these folks :

http://www.renm-performance.com/tuni...rmance-tuning/

(E60 SMG M5 owner too, but always looking and I think the GTS could be a replacement...)