By-pass valve

[Chander Balakrishnan]

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I have had a SJM 1.8 modification and a k24 turbo installed in my 1987
5kcsq.  The car drives great.  Every time I let off on the gas pedal after
accelerating to shift gears, I hear a loud shuddering sound from under the
hood.  I take it that this is due to the absence of a by-pass valve.  Some
questions:
1.  Why didn't I hear this before the SJM mod, or do not hear it in my 1990
200 quattro wagon ?  IS it due to the higher boost pressure with the SJM mod
in my 87 car ?
2.  Can I cause damage to the car by not having a by-pass valve ?
3.  Will a by-pass valve also improve performance ?  I recall reading a note
by a lister (Ben Swann ?) that he felt a subjective improvement in
performance (due to the turbo staying spooled up ?)
4.  I am not very handy, so if I wanted a bypass valve set up installed,
would buying a 1991 200 20v intercooler/by-pass valve set up be the way to
do this ?

Thanks.

Chander


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