i dont think a swedish inlet plenum will do for na form as im guessing its designed for forced induction otherwise im sure you would see more swedish plenums on na cosworth engines, you will need twin 45's at the minimum as an inlet, the small turbo rocker cover wont fit the cylinder heads that use the old style rocker cover, and to make that fit requires ally welding and then drilling for new bolt holes to be made which i imagine will be more expensive then buying a small turbo head unless you know someone who will do it on the cheap, hence why i just went and bought a small turbo head, dont make the mistake by thinking a highly skimmed cylinder head will help in the na process either as the valves get too close to the edge and the engine will run like crap due to leaks etc in the valve seatings and be of no good, and to get 180bhp out of a cosworth na form isnt easy atall, i was originally going to do a cosworth in na form and then looked at the money involved to achieve just around the 160bhp mark and it was rediculously stupid when you could go and buy a 2.0l zetec add some performance parts and be running 200bhp for less then £300, but if your not bothered about power and just want the engine running with a twin cam and looking good in there which says cosworth then just change the pistons the na ones or use the standard 2.0l pinto ones and hope valves dont hit, wack a na inlet cam in put whatever inlet manifold on and just drive it cheap and easy, it will run it will be quiet it will look good but a saxo will still go flying past you despite your engine having cosworth written on the top as i imagine you will still only get just over 120bhp if that, look into some of the people who have done na conversions and reaching 230bhp how much money they spend and how loud/rough running the engine sounds because you need solid lifters for you to get the power out of them, having said that people have still had 300bhp out of them in na form with stroker kits etc