Lately running into blowing fuse, when I start up the car. It even blows 20a fuse. I'm running RSX ignition coil. Now I'm on the 30a fuse. What's seem to be the problem here? Anybody running into similar issue, please give me some advice.

 

Stop going to larger fuses. The fuses are rated what they are to protect the wiring. You have 10A rated wiring going to the coils, meaning they can handle occasional 15-20A safely, 10-15A steady. When you put a 30A fuse in there the you are allowing nearly twice the current the wiring is designed for and you are going to make matters worse if the sheathing starts to melt.

Unplug one coil at a time and see if the fuse blows to isolate it to a single coil. If you can't isolate the problem to a single coil, unplug the COP harness altogether and check. If the fuse doesn't blow with the COP harness unplugged but does with any/all coils installed, the problem is in the COP harness. If the fuse still blows with the COP harness unplugged entirely, you have a problem with your wiring.

 

only happens with COP setup. When I put my stocker back on, it never blow any fuse. I think there might be problem with harness on the plug.

 

Do like I said. Unhook the coils but leave the harness, if the fuse doesn't pop it is a coil. Reconnect one coil at a time until it pops again indicating the bad coil. If the fuse pops with all four coils unplugged, and it does not pop with stock set up, your COP wiring is jacked.