i apolagise in advance, exhaust question
 

Looking to change the exhaust on a series mcrae. Money to spend...about £500. Changed the back box to a powerflow bout 2 years ago. 2 that i'm interested in is the scoobysport exhaust or the ninja exhaust. Either one i know will be good, but what i want to know is.... I know if i decat the whole lot i'm gonna get mot probs, so, can i just decat the downpipe and leave the cat in the centre pipe? Would i gain much acceleration? Or would a sports downpipe and de cat the centre be a better option? What i'm looking to gain is a neat sound but not tooo loud and more boost on a nifty acceleration! I guess the car is only 208bhp and has a top speed of 143? (even though i got 147mph in France, the misses messed her pants when she saw!) Any comments? (I know this question has run the mill, but most of you guys seem to know what ya talking about.)

full de-cat and decatted down-pipe then put the catted centre back on for mots
downpipe approx- 200
centre approx- 80
back box approx- 220

total- 500 smackers ;-)