if you have a tfo then this upgrade get the core machined http://www.ebay.co.uk/itm/Turbo-Upgrade-Compressor-Kit-SUBARU-WRX-Forester-TD04L-19T-w-Billet-Wheel-/112271382938?hash=item1a23e5599a:g:mJYAAOxyNDhSYiMR or 19T machined core http://www.ebay.co.uk/itm/Kinugawa-Turbo-Bearing-Housing-fit-SUBARU-WRX-TD04L-13T-15T-19T-5mm-Heat-Shield-/262839722893?hash=item3d3277e38d:g:st4AAOSwo4pYmDCU for my self im thinking of this with a ct9b turbine shaft and housing to bolt to 4efte ??? there 43 inducer 58 ex rufly same size as 19t http://www.ebay.co.uk/itm/Turbo-Thurbocharger-f