:confused:Ok this might seem like a stupid question to some,where is the difference in the different size exh housings if you change the hosing do you have to change the turbin wheel to match the housing or is that what makes the difference is the gap between the turbin wheel and housing is that what causes the spool and the egt issues? the reason I'm asking I'm getting ready to build me a set of twins the last time I asked abought this someone thought it would run hot using the 12cm on my HX35 the thought here is I'm a diy person and cheep at that so if the only difference between a 12cm and a 14cm housing is the size of the hole could'nt I put it in my mill and bore the housing instead of paying $500 dollers for a new one keep in mind the reason I'm building twins is cause I can build them cheaper than buying a new single and the fact that they look cool helps to:-laf