Looked at that but there seems to be some questions on the the strength of the wheel due to only having 15 or 16 bolts holding in the centers, i have seen some have had the inner and outer lips welded together to get past this, its an expensive upgrade to do.. would be interesting to see what the insurance would say also should you have a crash and kill someone due to a a home made untested wheel failing..
the RS714 is a nice wheel even in 18", i am on the look out for either a 9" or 10" barrels for the rears.
On another note if anyone wanted a set of these Rimstyle in the uk bought a load on NOS stuff from BBS so they are available for £1200 a set new. 18x8.5 et38