dont need a 2ltr ecu at all for it to run, you do need the 1.8ltr sump and oil pick up as the sump bowl is on a different side to accomodate the front pipe, the water pump flows in a different direction on the 1.8 which is why you need to change this too, also keep your original inlet and get an rs1800 throttle body as they`re bigger, if you do fit an rs1800 ecu make sure its correct as the earlier rs 1800 and 2i had similar ecu description one is 2fdc the other 2fcd cant remember which is which, when you fit these you need to rev the engine at 2,500 rpm for around 20 min for it to program itself to suit the engine, you will hear the revs alter several times even though your foot will be in the same position,if you just plug in the ecu and run it,it will be ok til around 3,000rpm then it will feel like its holding back,its well worth doing as i had a 2ltr 2i a couple of years ago and it was so much quicker than standard, especially midrange, you could also dump the exhaust manifold if it has the egr pipes on it as they poke quite far into the exhaust ports restricting gas flow, can find a non egr manifold on some escort 1.8si`s but not all hope this helps,roy