I've seen it stated before that the newer 3rd gens w/ speed density generally run faster ETs than the MAF L98s and not far off of LT1s.

Is there really much of a difference? I know that there are also other differences in years besides the SD, but are the 91 & 92s faster than the rest?

Thats because the later L98 cars had improvements, not because of SD.

What improvements? Don't tell me dual cats.

Nope, although that is 1 of them but that was an option already on MAF cars in 89. It was due to the switch to lighter weight pistons, same year as the SD switch.

hmmm... lighter pistons, not exactly a bolt-on

Yeah, but thats what I recall.