I have TTS on my 02 and they are a great fit and all that but they didnt give me jack for HP gain, I have a set of TPIS that are going on next week. The TTS have a 1.58 tube not the best for the 02 LS6 the TPIS have the 1.3/4 tubes mch better for the LS6.
I have the TPIS long tube on my 01. Took me about 6 hours to install. Only welding is to the converters.Very happy with the performance, fit and finish. If you have any questions, PM me, and I'll get back to you. Baron