If you do not remove it and it fails when driving it will pull particles into the cylinders (RI P) there are headers that cost about 400 and the sound difference is worth it alone. remove the O2 sensor and use a screw driver to crush the stuff and clear it with compressed air less money and you don't have to worry anymoreRead through the sticky. How much is the pre cat removal? Is it nessasary? Car has sat since 2013 in a garage in Phoenix AZ. It hasn't moved since. It's a 2002 SMG in perfect condition. The tires are gone. I'm having it towed in. This mechanic I'm not 100% on because they put two different treads on the car previously, they couldn't be bothered to find the two sizes with the same tread, but this is the closest mechanic. I topped up fluids and put in new battery. She fired right up. Mileage is 12,360. The price is $8,340 but will be negotiable after repairs at the mechanics. What should I expect? Fuel pump? Hoses, belts, tires (of course)? After the repairs it will need to make the drive back to Washington state. Mostly concerned about this pre cat I didn't know existed.