Not being funny mate, straight-through exhausts aren't legal. Either it's not straight-through, or it's not legal, one or t'other. Or it's a dodgy MOT, but i think you covered that.
If someone'll give you £800 for it i'd snap that up pretty quick fella, good price for what it is.
If someone'll give you £800 for it i'd snap that up pretty quick fella, good price for what it is.