My mate has got an RB5 and recently fitted a HKS super racing flow filter, problem is that since then he has had 2 AFM's go on him so he's changed back to the original filter.

Any ideas why it would do this?

 

in a nut shell, it is because the MAF sensor on the MY99 and MY00 cars is a bag of crap!
It's pretty damn sensitive and doesn't like induction kits, particularly if they are quite oily as it damages the sensor and causes it to read incorrectly.
If you do a search on here you will find loads of posts regarding the MAF sensor on the 99 and 2000 year cars.
The recommended method seems to be to use a performance panel filter, either the STI (needs to be replaced) or the K&N panel filter and be very careful when you re-oil it.
The ITG panel filters seem to get bad press on here too for breaking MAF sensors

James

 

Thats for the help, I'll let him know and tell him to get a panel filter, he'll be gutted he won't be able to get the nice sound from a big filter, oh well at least it will work.

Thanks again