Demand Engineering Ltd
Lewis Farm
Pettaugh Road
Stonham Aspal
Stowmarket
Suffolk
IP14 6AU
I think they charged be £550.00 for a double back box and a reworking of existing collector box. They cut the ends off the old collector box and fitted 2 new packed ends and then ran the pipe work down to 2 new smaller back boxes, rather than a single box.(the collector had previously been gutted and I wanted something a bit quieter) and then up to the first set of cats, their work was super. I think without the collector it was £350 or thereabouts.
Really friendly chaps and If I am ever in need of another handmade exhaust I'll be popping along to them.