I havent seen any great proof that BMS box is a solid tune, all post say its great fro throttle response.
If you want a cheap tune, that does not adapt/flatten like the BMS box( it needs restting sometimes). Your cheap sub $400 options are:
and perhaps someone else that tunes e46 m3's for a resonable price
128i Sport 6MT converted to Euro 130i spec, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE
In-progress: e46 m3 trans mnt, e36M lip Wishlist: m3 susp, n55 eng mnt, headers, LSD, finn dif e60
"The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is