secondary air filter, what the size? i need a new one.

some thing like this do?

HIGH QUALITY MINI OIL AIR BREATHER FILTER - 18mm RED

HIGH QUALITY MINI OIL AIR BREATHER FILTER - 18mm RED on eBay, also Engine Tuning Parts, Performance Tuning Parts, Car Tuning Styling, Cars, Parts Vehicles (end time 22-Apr-09 19:01:07 BST)

thanks.

I assume your on about the secondary air system, this takes it's air supply from the standard airbox and is filtered by the panel filter.

ah but im putting on a carbanio and the small filter is a bit shagged.

Ah I see. I'm not sure on the breather pipe ID but it easily unclips from the airbox to take the measurement.