Need a bit of advice about air filters on my 1.4SPi Mk3 Astra.
I'm wondering whether it's worth changing from a standard air filter, heard that there are some problems when fitting cone filters, and I'm not sure if there will b a noticable difference in just fitting an uprated panel filter.
Also, can anyone recommend a good exhaust system/backbox?
I guess every little helps, so it'd probably be worth replacing the filter. A lot of people fit cone filters purely for the noise. If you use a cone filter without a proper cold air feed, the engine will suck in loads of hot air which will in turn reduce power. If you could set up a good cold air feed from the front bumper or somewhere and block the filter off from the hot air created by the engine, it would probably be a lot more effective. People with 2.0 16v engines complain about kangarooing when using cone filters. This doesn't seem to be a problem with the 8v engines.
An uprated panel filter is favoured by a lot of people, simply because you retain the original airbox - so no unwanted hot air - and the filter is more free flowing, so you are letting more cool air into the engine, which will produce a bit more power. Drilling holes in the airbox can also help increase air flow
As for a decent back box/exhaust system, I'd recommend Piper because they seem to fit nicely, they give off a nice deep roar and an even nicer burble when you back off the accelerator. The price isn't too bad either