if you've got the cat on then should pass emmisions so long as cats ok and car runs well...silencers have no effect on emisions just noise.

by having no silecers though it will be fucking loud and on a long journey will drive you insane. i'm no mot tester but if its insanely loud they may fail it!!

i have a mk1 2l focus with 4-2-1 manifold (acts as a decat too) and milltek cat back (only the one big silenceer) and thats about 98 dB at 5k and is really loud on motorway runs so i'd advise against ditching the silencer completely. still wont be asloud as mine though if you have your cat still on.