I just received my warpspeed y-pipe and hi-flow cat today. I'm wondering, what size is the stock b-pipe? The new cat is 2.5" on both ends, will I be needing a new b-pipe? (Or maybe catback since my muffler is rusted out?)

Also, could anyone chime in on how much low end torque you lose with this setup? I've been reading that it's a trade-off going to 2.5" for high end power at the expense of low-end torque (due to less backpressure in the exhaust). Would it be noticeable in real-world driving?

Should I go with a 2.5" b-pipe or stay with the stock 2"?