i am in the process of picking out some stacks for my 01 and was wondering if i should just get a stack kit or get turbo back stack kit. i would like to increase my exhaust size because i have a tw on the way. how big is my stock dp on my 01? i believe its 3" but not sure and if i go with a turbo back stack kit it should come with 4" all the way back, correct? i think with the power of the tw i am going to need at least 4". does anyone make a 5" downpipe or is that overkill?