Porsche 911 exhaust mod


They don't come much more iconic than the Porsche 911, but without the sports exhaust they lack the sound you would expect from a Porsche, I suspect those crafty marketeers at Porsche thought everyone would tick the PSE (Porsche Sports Exhaust) option when they spec'd the car up after being underwhelmed by the non PSE system.. well I've done enough 911s to know not many people ticked that box :)

This mod is known by a couple of names mainly the PSE hack or the Gundo Hack (named after a forum username) the mod is pretty simple, its basically a pipe between the inlet and outlet pipe meaning you can partially bypass the silencer, the PSE system acts in the same way just with a valve, though everyone with a PSE has the valve open constantly anyway making it pretty pointless.

here is a box I modded: 
















The 996 and 997 have slightly different pipework but the mod is exactly the same....I use 1.5" stainless pipe and stainless welding wire, so no issues with rust.

now onto the sound.. the 996 and 997.1 all sound pretty similar, beefier the beefier the engine but the same kind of volume increase from the mod.

Matt a video Blogger here does the best run down of the mod for the 996:

There are probably 1000s of videos of modified 911 exhausts so I'm sure you could get lost on youtube and go exhaust note deaf eventually but here is another one of mine: It's a 997.1

The 997.2 is a different beast, as anyone who owns one will know, its a different engine with an extra silencer, though even without the extra silencer its a quieter engine overall, the mod is exactly the same again only the result is not as aggressive as the 996 and 997.1.

 the only difference in removal method is between the rest of the range and the 997.2, the 997.2 I need to remove the bumper as the fixings are in a completely different place to the previous gens.

Removal on the 996 and 997.1 can range from OK to very difficult, but having done over 400 of these if not more, I'm more than at home with every eventuality.

two clamps and 3 bolts hold the system in position, the clamps tend to be ok but the nut/bolt holding the clamps tight tend to be rusted beyond recognition, here is a picture showing after bolts have been replenished with stainless items:

the 3 bolts holding the silencer itself in place 90% of the time at least one snaps and sometimes all of them snap.. I replace each one with a stainless nut and bolt, heres one with only one snapped and an after of one that had all three snap:

There is no extra cost to any of the above issues as I class it all as part of the standard mod, except when a clamp is beyond repair, but these can be picked up at eurocarparts for under £20.

The following is extra on top and I do encourage all owners interested in the mod to check out the state of the bottom seams on their silencers, I offer repair of the bottom seam as well as the corner if needed, £40-£60 per side depending on how bad and how much needs repairing, this is all done again with stainless steel, here is a before and after:

I cut away as much rust as possible then shape a bit of stainless sheet metal and sleeve it over the area, then weld into place, this gives the silencers a good few more years life, the ones pictured here were not too bad and it was preventative measure rather than fixing a blowing seam or bits hanging off, which I do find!

another repair I offer is the replenishment of the Cat to manifold bolts, again 90% of the time you will find these only vaguely resemble a nut and bolt, this is £50 per side, it's not a fun job as access is limited and they are tack welded in place making drilling them out difficult, here is some after my work :)  you can see nearly all the aspects in the picture, the mod up top, the cat to manifold repair right in the middle and the clamp repair bottom left.