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HKS bypass part #

Got one,

Well I run the HKS bypass on my Xr.  Had it for years.  I can't vouch for
its' life span at 2.9 bar however.  I don't run those pressures.  It is a
good piece.  I put it on instaed of a very small piece Spearco sell.  Many
Xr owners run the Bosch piece at 1 bar and even higher.  No reported

Part number 3570XX-00000L is for a left hand HKS compressor bypass, add an
R to the end for a right hand.  This would refer to the direction of the
outlet tube.  

These are made to mount to a steel tube or an alloy tube you splice in.  I
use the alloy part on the Xr as it has long steel tubes.  On an Audi you
should mount it as close to the throttle plate as possible.  With our
rubber tube IC this may be a problem.  The biggest alloy tube they make is
50mm and you'd need to add some flex rubber tube to each end and deal with
angles.  But 50mm is too small.  

Part #3575XX-10000X is a steel weld on flange you can bolt the valve to. 
Now if you had the flange and welded a tube to it then you could run a hose
to the bottom of it as well and use it as you do the Bosch part.

Also listed is a Starion bypass kit.  From the photo is looks as if they
have added the flange and tube to the bottom already, but this kit is $236
list.  A valve and a flange would cost $65 list.

I have a Bosch valve for the Audi (88 5ktq) and I've modified an end tank
to accept the valve. I've added a take off for it above the divider on the
end tank.  I know some have put it below the divider and one of the
junkyard ICs ('85 5kt?)I got had a port already there below the divider.

It's been my understanding that you want the valve as close to the throttle
body as possible.  This will dump boost from the whole IC and tubes rather
than just from the turbo to the first half of the IC.

Will it make any diference?  Dunno. It shouldn't be worse than below the

 Audi didn't do it this way but then they were only recycling about .3 bar,
not 1 bar.

So there is some HKS info.  These could be run open to the atmo for dump. 
We've talked about that so I won't go into it.  They should be run back to
the turbo inlet.

These are not the bell mouth open scare the pedestrian type of blow
off/dump valve.

Have fun