Sreeram - hope you've had a chance to experiment and find the ideal customization for your game. I have a pair of IG Rad Pros. One plays slightly head-heavier than the other, but weight-wise they are only about 1.5 grams different.
To match the lighter one, I tinkered with 2x2" of 1/4" lead at 12, then tried 4x1.5" of 1/4" lead at 10&2. This is in addition to lead under the grip and Tournagrip. This brings them to roughly 338 grams and 6 pts HL.
Having used all of the Radical MPs from Liquidmetal through Youtek (non-IG) the IG Rad Pro is among the best if not the best in terms of stability in stock form. While you can certainly feel the flex on shots in the upper hoop, I don't think it lacks in stability. Perhaps once you find your ideal setup, your issues will remedy themselves.