Hi guys - firstly, a BIG thanks to Ian C for your very helpful info regarding the sequential turbo system. Needless to say, I have big problem ! Symptoms - No 1 spools up, but not to "peak" - power delivery is smooth but sluggish. Boost reaches 0.00 on EBC, & doesn't go any further. 2nd doesn't spool up at all. Haven't "pushed" it beyond 2.5 - 3k revs in case I do some damage (although it struggles beyond this point anyway !) When running correctly, there's a loud audible "rush" from dump valve - This is obviously not working (no sound) With ref to Ian's info, these symptoms sound like the IACV may be "stuck" open (?) I've checked the vac. hoses where possible - all seem ok & in good condition (only done 40k miles by the way) Can IACV be checked ? Any advice would be most appreciated. Also, if I cannot solve problem, anyone know nearest expert in this field where I could take it ? (Cheshire area) but dont mind travelling if have to. Muchas grateful !