on my truck in front of the resonator(which is in front of the muffler?)theres 2 diff sizes of exhaust pipe. theres a 2' section thats a lil smaller then 3" then it goes to 3" to the downpipe? this is definatly the most confusing stock exhaust i have seen. but i wanna put a turndown on the 3" part...so i figure a 3" ID cheap turndown from like autozone will work?