Dan (shglbmx) said everything. I tried to give you rep, but I need to spread it around first, haha.
Anyways, the exhaust is sold in separate pieces due to the fact that some people enjoy to customize. The mid pipe allows for the exhaust tuner to use their mid along with another brand's axle back. This is becoming very popular with many lines since their are multiple axle-back only out there.
The clips sound very good guys and I truly appreciate it!
Also, remember we have an additional limited time special so do not pass it up! I have extended this special to Thursday.
Have a good night