Great alternative solution to spending $700.
Good looking job as well.
I too have fabbed up a couple of DIY systems over the years, for sure a dyno test would not confirm optimum performance but then for $$ in pocked 97% is perfectly acceptable, and that is not counting the satisfaction of a DIY solution.
Was mentioned a possible heat problem, easy cure; couple of spacers and tack weld a heat shield about 1/4" away from the manifold.
I do notice your outlet is upwards facing.
Rather than the tin can cover you might wish to add a flapper valve to keep out water.