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Peter Laidler wrote: ↑Wed Apr 24, 2024 7:30 pm Come a bit closed Nick as I don't want everyone to hear the good news...... During the late 70s, Unipart got together a vast selection of air filters in order to test their suitability to incorporate into the UNIPART range. They were tested over many months for 4 sound reasons. I say 3 reasons in reality but there you go....
Airflow, Through-flow, filtration and adaptability (over the whole range of vehicles that they catered for).

The air filter that came out as the all-round best performer was from COOPERS. And whenever you see a Unipart filter thereafter, it came from Coopers.

And I know this because one of the blokes on the trial was my old pal Terry and for many years I had loads of the filters to use on my MGB's and MGB GT V8 - and my Cooper S of course!

imack wrote: ↑Wed Apr 24, 2024 8:17 pm If you're looking for a relatively quiet filter setup, forget the K&N or MED items. The Vortz one or a modified twin HS2 filter box are the only ones likely to do what you're looking for.

Peter Laidler wrote: ↑Wed Apr 24, 2024 9:59 pm I agree that you don't want to mess up an original air box. You could easily make a top and bottom plate for each filter with circular induction holes cut into the bottom plates and bolt holes to match with the threaded holes at the rear of the HS4's.

4 pieces of 1.5mm or 1/16" thick alloy plate - cheap. Cut, drill and file to suit....... 1 hour!

imack wrote: ↑Thu Apr 25, 2024 5:12 am I've had K&N pancake filters with stubstacks and MED filter kit with stubstacks, but I've not used them both on the same spec engine. Both are loud, but not quite as loud as 2 1/2" Swiftune ram pipes currently fitted.

Peter Laidler wrote: ↑Thu Apr 25, 2024 11:07 am Just thinkin' on my feet here for a moment. But have you ever considered using/adapting a couple of the readily available used HS4 filter boxes. They can be VERY efficient if modified to induct air in through 360 degrees ( - as opposed to the usual single hole)