right what filter do you have fitted with your hks fmic, mine is a maf based apexi ecu so im limited on type, i have had to pull out my aps cak as it didnt fit with the pipe work of the fmic. are the HKS mushroom type filters any good and what power rating are they suitable for

 

HKS are cr@p for filtration Steve. Not sure about power rating though.

Personnally i would go for the Apexi. On a test, fitted to Supra's, they came out best, with the best filtration, yet great air flow.

 

Totally agree with the cr@p filtration of the HKS type, wont be putting mine back on when its finally rebuilt!
You could see fine particles of ****e stuck to the inside of the maf housing pipe when i removed it so obviously got further. Give it a good oiling before using it too (since im running without MAF).