The threads don't give a full step-by-step with torque figures, but between them they show how owners tackled the job and where it goes wrong. For a sheared hanger, see Dropped exhaust and the hanger bracket.
Does the clam have to come off?
Owners differ. It seems to depend mainly on the size of the new box.
- A garage changed one owner's with the clam on and the centre undertray off, although the replacement was smaller than the box it replaced.
- One owner says Milltek boxes are "mahoosive", so either the rear clam or the cat will need to come off.
- Another says the standard silencer comes out with just the rear undertray off, because the bottom of the clam flexes enough. A third says no need for the clam off.
- Another says you have to take the cat and downpipe off to get the standard box out.
- One owner who has done it several times, with three different sizes (one huge), says take the undertray (diffuser) off and, sometimes, move the manifold. This is needed with a big box to move it out of the way, and you have to take the sensor on the left rear out. Another says the manifold does not need to be removed. A third says to just take the downpipe off the manifold for more clearance, via three brass nuts on studs that you reach from underneath. A fourth stresses the difference between manifold and downpipe.
- One owner explains that the system generally goes manifold, cat section, backbox, with a U-bend between the cat section and the box, and perhaps another between the box and the tail pipes. With a large box there may not be enough space between the clam and the cat section, so loosen or remove the cat pipe so it can swing.
See Rear clam removal if you decide to take it off.
Tips from owners
- Jack the car up as high as you can. A warm garage and the car up in the air make it easier. One owner gave up on his drive, in the cold, with the car on bricks.
- Rusted nuts and bolts on the connecting flange are the usual problem: one owner spent three hours with a hacksaw, chisel and grinder on three bolts, then fitted the new Piper in 20 minutes. Refitting is easy, he says; getting the old one off is the pain.
- Fitting a VSE was said to be a lot easier than getting the standard box out.
- Gaffer-tape the clam around the tailpipes so you don't scratch it.
- The worst part is usually bolting the diffuser back on, according to one owner.
- Several threads end with owners saying it is a pain and they wish they hadn't bothered. Others say garages don't do it much better and charge a lot for what isn't that hard.
What garages charged
- About £40 to swap a backbox (a local garage, 2010).
- Under £80 for fitting a new exhaust (an independent, 2009).
- £300 for a custom-built and shaped cat-back exhaust, fitted (2010).
One owner warns to make sure a garage knows what it is doing and doesn't damage the car in the process. The threads also note that the older threads about Milltek, VSE and Larini fits include step-by-step instructions and are worth searching for.
Help wanted
We don't have torque values for the flange and manifold nuts, or photos of the order of work. If you have fitted a box, please tell us how you did it and send pictures.