I've been digging out some of my old stuff recently - Toyo asked what my reasons were - well, none really, I'm just digging out some old stuff when I did a lot of mk1 Golf/ABF-T stuff that some of you may find interesting/thought provoking, especially if you're going to go to the lengths of designing and fabricating your own stuff, listen to everything I say/ignore me, makes no difference to me! (Actually, if I'm being honest I looked into everything of this inc. custom parts manu back in the commercial days so I'm kinda jealous that you're still ABFing it! I still want an ABF-T mk1!). So.... just noticed this pic I rescued - exactly 7 years ago today by the looks of it! ABF Carbon Fibre Inlet Manifold - Copy by Rick B, on Flickr EG of early mk1 designs and some things I went through over the 2 years or so of geeking out on it if you're going to design/make your own parts and any test data I put up - all air based so no reason not to evolve the thread as best poss imho; TWINNY,RAD AND SHROUD - Copy by Rick B, on Flickr inside intercooler end tanks - Copy by Rick B, on Flickr END TANKS - Copy by Rick B, on Flickr One thing I wanted to mention was one of the strong forces you need to manipulate if you're designing things and looking to do the best if you get the old 3D printing bug & not just on ABF - namely Gravity! You've no forced induction so that stone of pressure per square inch can help somewhat if you're designing things! Here is air fighting against gravity and turbulence somewhat increasing speed on it's way up(remember my tests are FI, also some slight syphoning much like a wastegate might work); Pipe Tests 3 - Copy by Rick B, on Flickr Divided feed gas speed by Rick B, on Flickr CFD Noobs look at the above pic to see where it gets darker blue at the top v more yellow at the bottom, gravity/path of least resistance example there! Like I say, I did all this many moons ago, this (below) is the kind of pics I had, most I wasn't bothered by as it was such a pixelated set up I only tidied up for others to think about such principles...... some turbulence/bend/more open orifice quick look as an idea (p.s. changing pic sizes etc messed up the look, the arrows in flow etc so sorry about that!); MONTAGE - Copy by Rick B, on Flickr I had to do this when designing ABF Turbo cast stainless steel exhaust manifolds back then as an example, but they were a dying breed back then, let alone now, so you may not have to fork out the £10k+ on the design/development of an SS mani or negation thereof which were my tests, but if you're going to go to the effort of either designing your own parts or look at an air-box thread then I'll stick some gas dynamics/ABF focused/pretty pics with some simple statements for anyone interested in the hope it helps you think a bit more about it! I doff my cap to those still going old skool too!