this is a great product. i am running it on my 335i and will be installing it on my girlfriends 135i once it arrives. it the only plug and play tune on the market right now and is just amazingly easy to install. doesnt ever give limp modes or check engine lights and makes the car run very powerful.
there is a 7 day money back gurantee on the product as i was told. try it out run it for a few days if u dont like it return it! awesome deal. i think there is also a 2 year warranty on the unit itself. it is impossible to trace once removed aswell.
btw here is a members dyno from today who did a before and after with a SSTT(split second turbo tuner) and a drop in K&N, gained 49.6WHP and 52.6WTQ
2008 335i Sedan Stock Dyno Results - Page 2 - BMW 3-Series (E90 E92) Forum - E90Post.com