Mine passed the MOT with a side exit..i took it to centre known to be strict too as i wanted a 'proper' test on it.

As mentioned already tho, IMO it is too loud to use everyday (especially in a cabby). Mine isnt straight thru either its 63mm into a (100mm dia x 600mm L) silencer, then out of the passenger side. Cost £150 for the bits an pieces (pipewerx.com..good lads) an £40 to have it welded up.