you could also try "4 xtreme" also know as 2 xtreme, very good quality, they have done quite a few max power cars, click the links section on www.essexracers.com for the details, i can highly recommend them, you name it, they do it, (its in essex)

powerflo,theres one in harlow, not to far from essex, but they are amatures, iv seen some of there bodge jobs, not the greatest place in the world, and rather pricey, 4xtreme is well worth a look!