I had an 84 242 with B21FT, bought cheap from a mechanic friend who drove it for several months with the wastegate actuator hose unhooked...he just wanted to see what the breaking point would be, but used some common sense in the process- premium gas only, timing bumped ahead a little, and backing off at any sign of detonation. Scary the punishment that engine took, and scary fast, too. When I got the car I reconnected the wastegate but dialed the boost up well beyond the point of the fuel cutoff switch - it was bypassed with a switch on the dash that also activated an air bleed valve (from a Turbo+ kit) teed into the wastegate hose - effectively giving massive boost anytime I wanted, but restored to a sedate and well-mannered car at the flip of a switch (any time someone else borrowed the car...) I'd estimate peak boost was around 20-22 PSI, and I did put a head gasket in about 6 months later, but that was with 220,000km on the original. I wouldn't recommend any of the above modifications for a daily driver - usually something will break, but this just seemed to be a particularly bombproof motor. That's how it goes - if I was trying NOT to blow it up, it probably would've.