Done the pre-cat delete on my GTI, defo notice a small difference. Turbo picks up slightly quicker, notice it through gear changes (manual) how the turbo is back on instantly.
Tried doing a boost leak test too, my pump wouldn’t build enough pressure.. probably didn’t have enough ummff vs leakage somewhere. I did find a small air leak coming from the front of the vacuum pump. Where the plastic nipple comes out of the pump. Not sure if I can replace that plus a seal separately or whether the whole pump will need to be replaced.
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