Both Audi and BMW have long, storied histories of making powerful six-cylinder engines ... or standard exhaust and filter upgrades for less restriction. As turbo and superchargers both generate ...

That's what this BMW Z3 M Coupe owner from South Africa thought, but since these cars are becoming a bit of a collector's item, he decided not to mess with its original engine and transmission pair.

In the March issue we tackled some common and not-so-common power adders for the S50 3.0 and S52 3.2 motors found in '95-99 BMW ... Z3 M Roadsters). We followed that in April with engine upgrades ...