i use the big headers and pipes by "default", not choice. i use the tti recommended 3" dyno max turbo reverse flow mufflers. after getting parts together i had a conversation with a dyno max engineer, and at that time dyno max gave flow numbers on their mufflers, the engineer told me a 2.5" ultra flow would flow more air than the 3" reverse flow. my car is strictly a street car with a modified 440, sometimes no more than 20 miles a trip. the exhaust system is always wet internally from condensation which rots the mufflers sooner than i like. acidic water is a by product of combustion and can't be helped. now if i only did longer trips at higher speeds i could probably burn the water out of the system and everything would last longer. i do some road trips but not enough to keep the system dry. i seriously doubt that a smaller system with freer flowing mufflers would hurt performance much if any on what i have. plug changes would be a little easier with 1 3/4 headers, but with the angle plug heads i have the 2"'ers aren't bad. either way you go you'll like the tti stuff. you'll just have to decide what's overall best for what your doing, and don't fall into the trap of bigger is always better.