The LX and SI sedan rear underbody spoilers seem to differ slightly by the exhaust cutout. From what I've gathered, this involves cutting the OEM bumper for the SI lip to fit. I'd rather not do that to my LX, so I figured I'd just get the non-SI rear and be done with it. My question now is, do you think the HFP muffler will fit with the non-si rear underbody spoiler? Here are pics of the non-si lip.