I have a 95 tacoma 3.4. What is the benifit, if any, in replacing the whole cat back exhaust instead of the muffler only. In speaking with two seperate muffler shops, they both suggested replacing the mufffler only, and not the whole cat back system, keeping the stock pipes. They both quoted me a flowmaster 40 intalled for under $100.00. Were they that honest and didn't want to take my money? Is there any advantage in replacing the pipes?