OK, so we took the backbox out of the system last night (well, Geoff @ CSG did, I stood and watched )

Sounds mean as you like now, proper growly, but looks like it lost around a pound of boost. So, as you do, I gave the death valve a twist to sort that out, but now it seems to have a bit of a flat spot.

If I accelerate in 3rd, it loads up as usual from 2800......... then at 4000 its like being hit in the back by another car Really comes on song, screams away and off I pop down the road. Strange.

Can MFi have flatspots pulled out with a decent set up by a tuner, or is that only EFi?