knocking @ 4k rpm

[maestro88]

93EX, F20 (yes, Indonesian version only 2.0L FI)
Short RAM intake w K&N filter, 4-2-1 header, 100k miles

Low end acceleration is good but knocking persists @4k rpm up to 5k. Just cleaned intake and injectors using those m/c with direct carbon cleaning systems. Tried using higher octane gas (RON92, US$1.70 per gall) instead of regular (RON85, US$0.95 per gall) but knocking still persist a bit (minimized).
Many mechanics suggest top engine overhaul but expensive and no guaranteed result. Any suggestions?

[TypeG]

it sounds like the bottum end is worn, but it is hard to tell over the internet. later.

[maestro88]

beyond 5k rpm acceleration is still decent up to the red line. Top speed for 2nd gear (at about red line) is about 50 mph, is that normal?

[TypeG]

auto or manual? i think i can get 60 out of mine. i take back what i said before. 100k is low to be worn out. but check the oil. later

[maestro88]

manual, for oil mostly used full synthetics SAE5W-40

[Boost_Lee]

ever alter ur timing in the past>? plugs n wire conditions?

[maestro88]

Just changed the spark plugs back into OEM made in Japan, it diminished the knocking but not totally gone. I'll try to change to better gas and see if it dissappear, thanx.

[KillerCam282]

Just changed the spark plugs back into OEM made in Japan, it diminished the knocking but not totally gone. I'll try to change to better gas and see if it dissappear, thanx.

What mark is your timing set to?