hi guys..since myvi have its catalytic converter hooked up so near after the extractor..how do i change the exhaust system if i wanted to keep back the CAT in the system but just change the piping size by a little,4-2-1 extractor,mid muffler and back muffler to enhance the power/torque and also sound..

have anyone heard of variable exhaust system,is it available in those " exhaust specialist shop " and if i really wanted to change the exhaust,is there any type of shop that can do it professionally except those shop that shows out " exhaust specialist " as their shop name(because it sounds not right,like fake)