Thanks for the suggestions.
The throw is approx 45 degrees. Will increasing this help in rolling faster or create more drag?

David:
Your reason seems very logical. I am using Futaba 3001 and I feel that at low speeds the aileron is really responsive.....it becomes difficult to control the model while landing at high throws. it is quite possible that due to the high speed, the servo is not holding the ailerons. i have a few 9202's lying around..... must try those next time.

Luke:
What is a blow back issue?

After trying the above, if not successful, the only way is to add more aileron area. I did the same on the rudder and now the model holds knife edge but will not climb. Again I am using 3001 servos for rudder and really feel that the servo is not holding up.

This is the first time since I started flying about 12 years ago that the servo holding power issue has come up. probably because this is only my second 3D model.

Regarding adding aileron throws to the elevator, I have made the provision to put 2 servos at the back with pull-pull setup while building just for this purpose but this really gets the CG out. The plane is already 2.4 Kgs with an OS 51 SX. So, I don't really want to do this until I put my OS 91 FS on it.

Thanks for the suggestions. I will probably first change the servos

Vikas