loud knocking as a matter of fact due to a spun bearing which resulted to a melted rod and a displaced piston..
so the thing is, do not EVEN drive it when the knock was there.
A new EJ207 can be bought for under 3K as well as get yourself a proper tunable
ecu like a PFC, ECUtek, Links etc. Also, fuel pump is also critical. never wanaa let ur car run lean again.