testing intercooler losses

[Nick Lawrence]

Subject is '90 200tqa with stock intercooler.
I added an additional pressure tap to the entrance side of the intercooler which is very near the output of the compressor.  To this I attached a mechanical VDO boost gauge. I also have a like mechanical VDO boost gauge hooked to the intake manifold. 
The purpose of this is to try to measure pressure drop thru the dual pass intercooler. My observations indicate two psi loss or drop. For example the compressor outlet reads 12psi and the manifold gauge reads 10psi.
I realize I'm also measuring drop from plumbing and the throttle plate and the mechanical gauges might not be accurate.  Some literature suggests 2psi  is about as much loss as you would want.   Anyone ever measure a 20v single pass at about 10psi or 1.7 bar?
Anyone feel a gain after replacing a dual pass with a single pass?   Any one (except Javad) installed an aftermarket intercooler?


 From other posts                  > I know the temptation to armchair engineer is strong with many of  
                                            > you ;-) but give thought to the fact that Audi didn't see fit to  
                                            > install (part or modification X)
                                                    I could suggest a number of very good reasons why part or modification X
                                            was never installed at the factory, and is a very good candidate for
                                            armchair engineering    (and everything else Mike Arman wrote)!
Just for fun!
Nick