If you're changing your car to look like something more powerful than it actually is, then it's probably going to look stupid.
Non car guys are unlikely to be interested or impressed.
Car guys would mock you. A quad exhaust on a 207 with 125bhp ? Who you foolin' ? Debadged or not, most people already know the lower and upper specifications of a 207. Even if it looks good the sound will be embarrassing coming out of such an exhaust. Don't think about cutting up bits of your exhaust to make it louder, either. It won't sound good one bit coming from that tiny engine.
If there's a real functional reason for installing a quad pipe exhaust system, say, you have extensively increased the power through engine swapping, improved intake and forced induction then yeah, it might make sense. Although why you'd do that on a 1.4L 207 would be beyond me.
Rough guide? Aesthetically speaking, for a modern car I'd say the following is acceptable:
0-200BHP = 1 pipe, 200-320BHP = 2 pipe, 320BHP+ = 3-4 pipes. Some exceptions for cars with AWD or LSD, I guess.
Mechanically speaking, it depends on whether you have a single or dual exhaust system. This depends on the number of cylinders in your engine. A 4 cylinder engine has one exhaust manifold whereas an engine with 6 cylinders or more will have two exhaust manifolds. You typically have 1-2 exhaust tips per system. For this reason, on some hot hatches you'll see 2 tailpipes. You may find 4 tailpipes on some deserving 4 cylinder hyperhatches for stylistic purposes such as the Mercedes A45 and even on not so hyper hatches such as the Golf R & Audi S3 - (which shouldn't get it IMO but hey, it helps them sell)
Fundamentally these 4 cylinder hatches still operate on a single exhaust system. However, the point is, the 207 isn't a hyperhatch and noone will believe it is one even if you debadge it. So forget it.