Changed the stock muffler with a B&B Spc. muffler.

Installed the carb velocity stack.

The performance difference was totally unbeliavable...

My Lanier Extra 300L ( 12.5 lbs ) was flying like a cub, now it flies like a guided missile.

Thanks everyone, especially RCIGN1, for their help.

Only problem left is the interference, done these :

1. Placed receiver aft.
2. Placed receiver battery aft.
3. Covered ignition cable with aluminum tape.
4. Rerouted antenna.
5. Had a gyro for the ailerons, when disconnected it helped a bit.
6. Changed receiver.

Anyone had a similar problem about the gyros ?? Any recommendatons to solve the interference ??

Thanks...

Yep. Get a Bosch plug cap from C&H Ignitions.

Nope, The Bosch cap won't fit the hex on the new Champion 10mm resistor plug..The plug is long enough but the cap is made for the larger 14mm plugs...
Maybe Bill will make a "hex enlarger" for the new spark plug to fit the Bosch cap