Switch injectors and nothing switch back and it runs? Please Help !

[UK_Daz]

Hi Can anyone help with a believed injector problem. Im doing a KAT conversion, changed the injectors to the 370cc SR ones, car will not start, changed back to original KA 270cc and car runs fine, I put a fuel pressure gauge on the fuel line and it holds pressure for a long time, changed back to 370cc injectors and pressure drops off quick after cranking the engine. So I think I have a fuel leakage from one or more injectors, I changed all the rubber O rings, big ones and little ones for new ones, and still not holding pressure, Can the injectors leak internally ? I thought the 370cc purple top injector was a simple swap, or is there something else I should have done may be to the fuel rail or injectors themselves? I tested each injector on a OHM meter and they are all at ".10" same as KA injectors. Running out of ideas, any help much appreciated. Cheers Daz