Best Upgrades for the 2.5L V6 in My 1994 Audi A6

I'm looking to upgrade my 2.5L V6 in my '94 Audi A6 for better performance and improved fuel efficiency I'd like to hear about upgrades such as intake and exhaust systems, camshaft swaps, engine computer tuning, and suspension modifications that would benefit this engine type any personal experiences or recommendations are greatly appreciated