It's not quite that simple,
What vyou nhave to bear in mind is how to replicate actual airflow into a cylinder and out of it with an intake and exhaust manifold attached as they have a big affect on how it happens.........
http://www.popularhotrodding.com/tech/0610phr_cylinder_head_porting/index.html
http://www.popularhotrodding.com/en...core/0412em_porting_cylinder_heads/index.html
The box I described does exactly that, vacuum on sucks air through the cylinder head as you open the valve, I agree it will be the wrong way round when you do the exhaust port but as Mr Vizard explained the exhaust side is less important than the inlet as you just need to get rid of the burt mix.
Intake and exhaust manifolds are already done for you if you buy decent after market items, perhaps with the exception that you may want to match them to the head first.
the only thing missing is you can not measure actual flow rates, but you don't really need them, all you need is to know whether you have improved flow or not and this does it quite well in my opinion.
HDi fun made a good point about going too far and hurting flow, the only way I can see of overcoming this is to use a head as a sacrificial head and just keep going untill it goes the wrong way then scrap that head and start with a fresh one with the knowlege you have gained then stop when you get the right readings.
None of this will be as good as professionally done head by someone with years of experience and the right machines, but I think you will get close for the cost of a second hand head and some playtime in the garage. as oposed to hundreds of pounds for a longman head or similar.
Tried it on an C16SE Vaux head and so far have improved flow by around 15% over standard acording to my figures. my intention is to have another go this winter and then try it on the Race motor and see what the rolling road says.
