If you replace the catalytic converter, it will make it more Eco friendly.
It may not seem low budget, but it will help you gas mileage, help the air, and in the long run save you money!
friendly (reasonable answers please)? i recently acquired an old white 1988 toyota camry with a messed up axel (which i'm replacing) and other than that it runs decent i was just wondering if anyone had any low budget suggestions on how i could make it 1. More eco friendly 2. Quieter (it's realllllly loud) 3. Faster (if at all possible i'ts really old)