I took my car to this garage with some performance issues, in particular the car was suffering lag. A GT35R was recommended to replace a T61. I raised eyebrows, and enquired about claims that the turbo would spool and pull strongly from 2500rpm and also asked about problems regarding surge. With the work about to commence, I suggested other parts were repaired and the car tried with the T61. THis request was ignored as ther tuner was so sure the GT35R would be the better turbo, but far from improving performance and spool up the GT35R actually made things far worse.
Other work carried out was reprofiling of cams to help with spoolup and a custom intake manifold. These are the findings of the internals of the intake manifold





Comparison to what it should look like





Is this good design?
This 'custom made' intake manifold actually flowed considerably less air than a standard manifold. Needless to say, rather than help with lag, this only served to compound things and make them worse.