Dougs
I had the exact same problem with my TTI. I bought thicker isolators from Summit Racing FOR BOTH SIDES and it cured the problem. The thin ones (just like yours) would not work.
These are the ones I bought and they worked perfect. You can't beat the price either.
http://www.summitracing.com/parts/PIO-A2469/
Gosh I hate that you had to do that to your headers.