They sell for silly money though now, £200 plus as all the turbo boys want em as the plastic manis cant take the pressure and theyre easier to add sensors or extra injectors too.
And the guy who says the difference between the C2 engines concerning the 15bhp is down to the inlet and map is sadly wrong, the 125bhp JP4 has more lairy cams too which make the biggest difference. Not all 125bhp JP4s were fitted with the alloy manifold, but all were quoted at 125bhp. For an NA engine I dont think theyre worth the money, only if your running a serious Nitrous setup.
Still a good find though mate