Hinduism is fairly relaxed and tolerant, but that does not mean it is a free for all thoroughfare. The Vedas are called shruti(s) - which means that no kind of alteration is permitted. When we are initiated into the religious practice during Upanayan, we have to exactly recite the mantras as is. Can I improve Bhagvad Gita by inserting/deleting 30 new verses? On the contrary, if you change even one syllable in a Rig Vedic verse, you risk invalidating it.
