Welcome at K20a.org @Ponna and @elifdenizer.
Yes, that's a safety feature we introduced for the Classfield's as we had more spammers there as interested buyers. For more information please contact @Them Witches, he is responsible for that sub forum.
Yes, you are right: unbalanced but forged crank, no oil squirters, weaker connecting rods (same as K24A4/A8 and K24A1/Z4), but some windage improvements on the block. The balancer shafts of that engine limit the engine speed most. A simple oil pump change would unleash for more in both, power and engine speed. We talk about around 5 hp and another 400 rpm. Anyway the crank assembly is a bit sub optimal for an high revving engine. If you limit it to 7400 rpm for occasional street drag, which would a challenge for the crank assembly, it would be ok. We have some threads regarding the tuning, bolts on and experiences of the K24A4/A8/A1/Z4 here, just do a search.
