its been done, its cheaper...

maybe the other side is missing?
but that one pipe looks to stick out a bit far

i think bullet has a good guess, its cheaper and easier to get a single outlet muffler.

off-topic:

Most know that I'm deaf and I don't often hear idioms. I once heard of "blue balls" and I asked my professor what it meant. Catch is that my young female interpreter HAD to voice it...

Needless, I found out what it meant...
/off topic

Someone who is cheap, OR someone VERY serious about performance. The split in our exhaust is actually a bit of a restriction.

restriction, really? i would think it to allow more flow

What it is, the gases hit the wall where it splits, and have to change direction. EVERY change in direction reduces velocity.

Having the extra muffler helps flow, but if you're going for serous flow, the split hurts. Get a freer muffler, eliminate the split, and you can free up a little power in the high end.

petraman was correct on the SC pulley. Also on the single exhaust tip.
Between the two that looks like a recipe for disaster.

That almost looks like a M62 Gen 2 pulley That'* TINY for an M90.