I installed a Spider Tuning Box today on my F10 520D.
The instructions were good except for specifics of how to access the fuel rail. The photos indicate you simply remove the top cover, lift a flap and there it is, but it's not the case. After removing the top cover you need to remove the air filter, air induction system, the flap and then you'll find the connector you need hidden under another rubber section.
A few more photos would've made this job much easier. As it happens I would've needed a mechanics help except I found instructions written by another frustrated customer on this forum (Link
http://f10.5post.com/forums/showpost...4&postcount=12
I've since done 100 k's with the system and it feels as though there is a little extra pull there, however nothing like the claims stated when purchasing the unit. I'm yet to decide if I'll keep it. Seems like very little bang for buck at this point.
Sword.