You really shouldn't say "in most cases" Tony because that simply isn't true. Any car with a T4/T3 hybrid will usually have more exhaust pressure than inlet (if a T2 exhaust side flowed as much as a T4 compressor, it'd be a T4). In all of the turbo cars we've measured, it was at least twice as much. The twin turbo big block mustang a friend had a single Y2k on had a 3:1 ratio! He then swapped to 2 88mm Y2K's. Have you measured your exhaust pressure on the Porsche? I'm not saying its impossible, but if it exists, its almost always on very high dollar road race cars. Drag cars generally have smaller turbines to help spool at the line which of course increases exhaust pressure.