This is my guide to fitting aftermarket air filters to Vauxhall Corsa's.

I tried it, all the claims that you'll gain power maybe true, if you fit a suitable exhaust system, and play with the injection system, but just fitting an aftermarket filter makes very little to no difference.

Test vehicle : A 1993 Vauxhall Corsa, 1.2 litre Single overhead cam (SOHC), 4 spped manual

Air filter : A big K and N style cone filter!

Plus sides : sounds nice when you rev it, something to talk about with your mates, accelerates slightly faster, only slightly though!

Down sides : you lose low end torque, making it harder to pull off smoothly, engine heats up quicker for some reason, coolant system can't cope if you sit in traffic for more than five minutes, top speed is affected as well, lower fuel ecomony!

Overall my experience of fitting a big air filter was not good, the engine roar was unbearble after 70mph, I couldn't go fast enough to lose my license, my coolant was boiled away after two weeks, and my fuel ecomony went down!

Reason being, engines need equal amounts of pressure from air intake to exhaust outlet to operate smoothly, upseting the balance either side doesn't do your engine any good!

I hope my experience of trying to improve my car helps you, it didn't work for me, what does work is a full service, oil filter, air filter, spark plugs and high grade semi synthetic oil, that will do more good then any £20 air filter!