Probably doesn't help much, but on my valver i have a straight through system from the engine down pipe to the back box. I have a de-cat pipe on, and it costs me £10 to have my cat put back on when it's time for an MOT.
With regards to pops, it's probably the loudest thing i've ever heard, it makes a nice burble when coming down through the revs if you rest your food on the accelerator, and if you're doing about 4k and you tap the accelerator whilst coming down through the revs then it will pop and sound like a gunshot, it's seriously that loud.
Not sure what effect it will have on a 1.2 engine but try a straight through system to a back box, if it pops too much or is too loud, stick the cat back in. Mine still pops a little bit with the cat on but you have to try harder to get it to do it.