Has anyone tried any of the TDI / HKS upgrades listed in the adverts on this site? The stage 4 supercharger, or stage 5 330HP conversion? I love my 91 LS400 but it's finally starting to get a little tired and I'd love to get it going a little faster. One mechanic I talked to said the GS430 engine fits without too much fuss. Does anyone have any ideas or suggestions? Anyone? :D