Yep Derrick does have an early series motor(pre A-series). Those engines from the start Mazda had alot of problems with. Derrick's problem surfaced when he put on a single turbo with a small exhaust A/R. The small exhaust housing allowed the engine to produce a ton of boost very early in the rpm range therefore putting alot more stress on that engines weaker design. Since 20b's naturally produce more torque than 13b's this combination cause the engine to slightly twist. He has since had the engine rebuilt and dowel pinned.

 

Right, that's what he said, I too have a pre-A series motor, as a matter of fact I think I have the ealiest one on the forum, (no I am not bragging) I have #048 any I am slightly worried about the same thing happening because I did not rebuild my motor yet, but I am using a 1.15 A/R so hopefully it will last until I rebuild...........hopefully