I haven't dealt with the Mosselman Turbosystem directly, but will agree that .4 bar (5.8 psi) is a pretty conservative amount of boost. Adjusting the boost up or down from this pre-set setting also is a VERY simple thing to change via a wastegate adjustment. Want more power? Turn up the boost! Admittedly the strain on the engine increases proportionately with every upward adjustment of boost, but even with a modest increase to 10 psi, hp would be much greater with very little risk of decreased engine longevity.

I have run bone a stock VW GTI with a Callaway Turbo System installed at anywhere from 10 to 14 psi boost, and have driven them problem free for over 200k miles! The Germans build 'em strong right out of the box!

J.G.