Best Air Filters

I asked a little while ago about socks on trumpets. Seem not to be the best solution and its possible for the socks to break up and get sucked in.

I've gone for proper (K&N) filters over trumpets - just make sure there's enough space between the top of the trumpet and the filter top.

Better may be an air plenum over the trumpets that is fed by a cold air pipe with a good filter on the end.

Surly unless you've got a GTIR or M3 sat in your local scrappy most stuff's going to be a single throttle body stuck on the plenum rather than ITB's, so the air flow characteristics are going to be quite different? It is a sound plan though, it's all about letting someone else do the calculations for you and then just copying it. . Just be careful that their hard work is on a close enough set up to yours.

Originally fitted individual socks but told they aren't very good.
I've now gone for an ITG foam filter purely because I could have the backing plate machined so the filter sits slightly higher and further forward to clear the brake m/c
there's plenty of room inside the filter to house ram pipes and, IMO, the plate joining the carbs should prevent them going out of balance

I can't say I've ever cut open a plenum myself, but it wouldn't surprise me in the slightest if a lot of them used trumpets within the plenum, I'm more talking about the throttle body's position. Surely for the airflow to be comparable to the carb's alolympic's using you'd need to be looking at a set up using individual throttle bodies between the plenum and the inlet manifold, as the trumpets in this system will be before the restriction of the throttle plates. Where as in most modern car's they use a single throttle body restricting the airflow into the plenum it's self, meaning the trumpets will be in the vacuum after the restriction of the throttle plate. I'm not sure how much difference this will make, as when fully open the throttle plate wont create much of a restriction, but it's worth bearing in mind/checking out.

Sorry, got a bit sidetracked and thought we were talking about using the actual trumpets dimensions too for some reason. I'm with you on this one, adapting someone else's hard work is the way forward.

So are you saying that most cars your side of the pond use individual throttle bodies now? for some reason I had it in my head that the American emissions laws usually restricted cars to a MAF metering system rather than MAP?