Oh sorry just read your post better, if it's small they have some stuff at autozone thats like a putty to repair mufflers, i have used it on my x-pipe and works wonders, hardens like cement but when you apply it just dab alittle water on it and it spreads really smooth, i think it's called muffler mend or something like that.
When in doubt pay the 60$ at an exhaust shop to just fix em up. You probably w/out numatic tools could not get them to tighten up enuff. its cheap and you will love it when there sealed up :0
I got some of that copper/orange RTV stuff at Auto Zone and put around each primary before putting the collector back on. That helped a good bit, but I still have exhaust leaks everywhere.
Talk to your builder. I don't think you want to mess around and void your warranty with the builder. Let him know what's going on. I'm sure you paid him a pretty penny. Make him do the work.
I got some of that copper/orange RTV stuff at Auto Zone and put around each primary before putting the collector back on. That helped a good bit, but I still have exhaust leaks everywhere.
You need to use some hi-temp copper as previous mentioned, unfortunately that is common with all multiple piece slip fit headers.... Permatex them up and they'll be fine.