Not that I'm a racer, but the benefit off the line and at speed from blocking the EGR and air recirc valve are huge. My car jumps off the line, and when that turbo kicks in... I can honestly say that I've never been taken by a 617.

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Chris

'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
'99 C280 Sport sold
'85 190E 2.3 sold