Hi, is it worth replacing the standard air filter with an aftermarket version, for example a K&N or Pipercross one? Is there any improvement in performance, or MPG?
I guess that the K&N would benefit performance higher up the rev range, but the 8 valve GD I-Dsi does not rev too high anyway (it starts to run out of breath at about 4500 but this is down to the 8 valve configuration rather than the shortfalls in the air filter). I guess GE VTEC would be more likely to benefit, would I fit one ? naahh
IMHO the 8 valve engine is more pleasant to drive around town and generally everywhere except maybe the motorway, but even then the 8 valve is pretty capable unless you want to go over 90 and get a ticket (we have been from one end of UK to the other in both a GD and a GE and I wouldn't blink at doing it in either).
Search for 'air filter' on forum there are people who fitted K&N and their experiences, but bear in mind differences between 8 valve and 16 valve characteristics.
