hey guys i'm new here, in fact this is my first thread! anyway, i have a 2000 Sport with the 4.0 SOHC and i'm looking for opinions or advice from ppl with firsthand experience about EXHAUST. I am looking to put a catback system on my x but i've heard so much about exhaust that i wanted some ideas from other explorer owners first. first off, i've heard that ford vehicles in general run better with straight through mufflers because the smaller but higher output engines (as compared to chevy or dodge) depend more on exhaust gas velocity to create power. i have also heard, however, that you can lose low end torque if there is not enough backpressure on the engine. currently i have NO muffler on my Sport, the exhaust pipes simply come out of the cats and dump straight down where the muffler would be. the highway passing power is great, but my off-the-line performance SUUUXXXXX. what i'd like to have is an exhaust system that is not too loud inside the vehicle but is still noticeably aggressive outside when i stomp on the gas. i'd like to keep a little highway passing power, as i drive on the interstate regularly but i'd like to be able to bark the tires on a launch. here are the setups i have considered.... magnaflow dual in/single out (for slightly more backpressure and possibly low-end torque?) magnaflow dual in/dual out (for good flow, but will backpressure be noticably low?) dynomax superturbo true dual (i've heard good performance reviews but how loud are these mufflers inside the cabin?) also, i'm open to suggestions from any of you! if you have an exhaust system you LOVE feel free to share it! and lastly, what kind of pipe size should i use? i know the pre-muffler factory exhaust is 2-1/4" but what size should i use for the after-muffler pipe, with each configuration? sorry for being so wordy, thanks guys!