G'day All, I have Rotrex powered 2.5L MX-5 that just won't maintain boost. I know I'm getting some positive pressure as I've blocked off the BOV and before things get too hot I'll get back pressure noise through the SC coming off the throttle but once the temperature gets up there's nothing. All the troubleshooting I've done is pointing to accessory belt slip on the water pump pulley. That pulley is supplied by Kraftwerks in their kit and it's a ribbed jobby to replace the OEM smooth and the main accessory belt has been changed to a 6DPK to suit (OEM is 6PK). The actual SC drive belt and pulleys are toothed and I just can't see them slipping so it has to be the water pump pulley... right? Any thoughts or tips appreciated.