Tenneco Clean Air India shares surged over 30% above their IPO price of Rs 397 on the first day of trading on NSE, listing at Rs 505. The company's market capitalization reached Rs 20,291.21 crore. Analysts cite strong investor confidence in its technology and OEM relationships, advising partial profit booking for allottees and waiting for a dip for non-allottees due to sector cyclicality.