I wasn't disputing the handling potential of the M42 equiped E36 VS. the M42 equiped E30. Nor was I disputing the fact that the M42 makes decent numbers for the size of the E30, or the fact that it is lighter than the M20 6 cylinder. All of the above are undisputed fact.
The guy was asking for performance "Opinion's". My opinion is what I stated. You can't replace displacement. Stock from the factory, the M20 "I" six cylinder will out number the same car with a stock M42 4 cylinder any time you want to put them on the dyno. His question was "is there much difference." I'd say that 34 horses and torque is "much difference".
You say that with a chip, the M42 can hit 150 horses. OK, I'm with you. BUT.....add a chip to an M20 "I", and it can go from 168 to a conservative 183...still 33 above the M42, for around the same price. Nothing has changed difference wise. Add to that a set of cheap 19lb injectors, adjustable fuel pressure regulator, and a decent exaust, (on either car) and you're going to get better numbers out of the 6 cylinder. Displacement wins again, and it always will unless you start using forced induction on the 4 cylinder...and even then, if you use the same boost on the 6, you're going to get better numbers.
Listen man, I'm not trying to start a pissing contest with you on which engine is better suited for racing or blah blah blah, I was stating my opinion, which is what the guy asked for to begin with.