help needed asap (uprated injectors) Ford Focus

so I have a mk3 Ford Focus 1.6 tivct N/A which is currently running a (stage1+) map but I keep misfiring which admittedly it was misfiring before I got the map but has progressively got worst over time after I got the map I had no misfiring what so ever for a few months then started getting the occasional misfire when it was cold out but last week I got constant misfiring while driving and sitting still so I changed the coil pack and all the plugs and removed the inlet manifold cleaned it out and checked the valves which was all okay but was still misfiring but not when sitting still and was still idling very lumpy tho so after taking everything apart I finally got a code for an injector fault code p0201 which is a fault code for the injector for cylinder 1 but this could be for either cylinder 1 or 3 so I pulled the plugs and it seems that both cylinder 1 and 3 are running lean but 3 was a lot worst than 1 soon I will be taking the car for another map as I will be going for technically stage 2 for an N/A car so was looking to see if I can find any uprated fuel injectors I can put in my car when one of my friends said he had some spare st fuel injectors which he said would fit so instead of going and spending stupid amount of money on new oem injectors I would try and see if the st injectors would fit or what uprated fuel injectors I can use in my car but I could not find any uprated fuel injectors for my car there just isn't any out there yes before anyone says if you get uprated injectors you'll need a map and better fuel pump I already know but just need advice (help) on what injectors I could use in my car that could handle more power and slightly increase the power of my car