Trickling sounds occur due to ignition failure. An easy way to check if you need an overhaul is to see traces of water in engine oil via your dipstick plus check for water seepage through your air filter. If either of the above then it requires an overhaul. As you say the car is fine except for the trickling sound I recon the following:
1. Get you spark plugs and ignition coils replaced ASAP - Can be done at Woqood.
2. Get your exhaust manifold, catalytic converter and mounts inspected - Any Exhaust workshop in Industrial Area.