Nice looking bike.
Those exhausts look like they are way to short, but that may be an optical illusion. In fact they look shorter than a TZ250G which revved to 12,000. An RD motor can't rev anywhere close to that without failing catastrophically, but maybe that isn't an issue if it's not going to do a lot of miles.
Which software did you use for the pipe design, or is it more of a form over function issue?