The exhaust ends:
You may want to consider:
When adding putty to their resin, first add a little cyano. It will seal the resin so the putty and resin do not separate later. I found I needed that on the ARRV, but more so where the resin was not homogenous. For deep holes, use Cyano gel and baby powder. You will find it bites better.
I was just painting the exhaust on mine, and the putty that was filling the hole just fell off with part of the resin attached. 
This was not one with cyano in it - I was told the tip afterwards.
Oh, and I am with the guys - Takom MK 11 would have been a better choice 