i have a 05 civic ex se. i want to know how do you know what the pipe size should be so that it won't touch the bottom of the bumper or can all exhaust be altered @ install

 

Usually anything will work. Mine is about 4 inches right before it comes out of the bumper and about 3 where it comes out of the cutout in the bumper. Civics are easier to put one on and look alright, unlike Eclipses (I don't know what else?) that have their mufflers installed at an angle unless customized. Just ask your local performance shops about it, and they can show you the kind of muffler that would look good on your civ. That way, you'll know what to look for if you shop online.

 

IF you get a good aftermarket brand name you should have no trouble with fitment issues at all. Also they have already done the R&D to get teh right size for your car. 3 inch sounds quite big for a NA civic. I belive the best is somewhere around 2.25-2.5.

 

Sorry, LEVIII. I was talking about the opening where the muffler protrudes out of the bodywork. Sounded like a fitment issue for his bumper. Didn't even think about the pipe size, was talking more about the components around the bumper cutout. But anyway, everything should be a standard fit.