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TINGY996

My Gundo Hack

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I started this job today so i thought i would share this for anyone who is interested. I know there is probably plenty of reading on this on other sites so sorry if i bore anybody.

So i may have cocked this up a bit by not taking off the rear bar but i managed to get the mufflers out anyway. It's really not as easy as people say, the nuts are really hard to get to as i am sure these were assembled to the engine at the factory. It is a PITA to get to and while i was laying under the rear my 3/8 drive socket slipped off the nut, fell on to the headers then fell between the pipes and onto my lip and broke my front tooth, i am not a pretty man and now i am even uglier.

It is very time consuming undoing the 3 bolts holding the bracket that attaches the muffler to the body, i also had to cut the  55mm pipe clamp bolts because these were cooked on. I managed to find another one at a wreckers here in outer Newcastle that have some 996's and Boxster's which worked out well for me, i am going there tomorrow to have a look at what parts they have so if anyone is on the lookout for anything let me know.

I will remove the rear bar tomorrow i think just to give me some more room to work, in hindsight it should have been done first up.

Tomorrow i take a visit to my Son's mate who has a car modification/tuning business to pinch some stainless tube and hopefully get it all Tig welded. 

I also had a crack at one of the exhaust tips as they were really stained, it came up pretty well i think, i might get the heavy duty polisher out and give it a go.

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You wont be dissapointed with the sound after the mod ,,,,best value for money Porsche 996 and 997 mod Imo ,,,gives the car the sporty sound it should have had from the factory ....:)

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Tingy

Have you decided on the diameter of the pipe being welded in? I've gone for 1.5 inch diameter on the advice of a seasoned expert from a YouTube video posted in another thread and haven't looked back. Mind you, my donk is a 3.4 litre.  Totally uneducated opinion here but assuming yours is a 3.6 litre, 1.75 inch diameter may be the go. 

When done and if you're still hankering for a little more "theatre" you may want to consider replacing the factory catastrophic converters with sportier equivalents.  Either way, you'll love it.

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I was going for 1.75" if i can get it, hopefully he has some off cuts for me and i will do the fab stuff myself and get the gurus to do a nice Tig weld for me;)

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I used a 1.75 Bypass pipe on my 3.8 S ,,very happy with it sounds good at low RPM when cruising  and gets a good howl about it when you get on it hard with some small pops and burbles on the over run ..Very sporty and what you would expect a Porsche to sound like ..

I know some go 2 inch and even larger 2.5 from my experience with cars running the larger pipe it is  just to loud for weekend touring and spirited driving on mountain roads .. 

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My 997 needs a little extra noise, has anybody added bypass valves into the Gundo hack to isolate the bypass when not required ? 

Maybe that’s a dumb question we all need noise. 

Warren

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22 minutes ago, WB997.2GTS said:

My 997 needs a little extra noise, has anybody added bypass valves into the Gundo hack to isolate the bypass when not required ? 

Maybe that’s a dumb question we all need noise. 

Warren

I looked at an aftermarket bypass valve today when i picked up the pipe i needed, not so dumb Warren and cheaper than Porsche.

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I finished the exhaust and after doing a 3 day road trip i can say i am pleased with the result, it's not exactly what i thought it would be and i am happy to say it's not droney sitting at freeway speed. It's only when you lean on the loud pedal that it gets more of a bark to the exhaust and up over 4000rpm the flat 6 sound is very pronounced.

I ended up using tube with a 42mm id because i got them given to me, not that i was afraid to spend some money but i was happy to take a donation:D

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My son helped me with the mod and we were allowed to borrow a brand new plasma cutter from where he works to try out, it has a built in air compressor so no outside tank is needed, it's a Chinese jobbie and i thought it worked very well compared to some i have used in the past.

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The holes were cleaned up with a tungsten rotary burr on a die grinder after the holes were cut to make the holes a bit bigger and keep a smooth finish.

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It's a finicky job getting the tube to shape and some of the welding was a bit tricky to get into some areas, this is the finished job.

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In the end i had to take off the rear bumper just to get a bit more room to work, it wasn't an overly hard job but getting the mufflers off is very time consuming.

Shaping the tube to fit as snug as possible is also very time consuming, this makes it easier to weld though so your not filling big gaps with too much weld. I also used a MIG welder as we could not get a TIG unit.

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Nice work, bumper off is the best way to go when changing mufflers - gives you so much more room to work and its a 10 min job to do.

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Nice work glad you are happy with the results ,,,certainly give the cars a better sporty sound ..

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@TINGY996, is the reason you went for the curved pipes rather than a shorter, straight bypass pipe just because you were given the curved ones?  It looks as though the hack is achieved by whichever option, do you think one is better than the other?

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I had looked at a couple of different ways these pipes were done and i decided for ease of manufacture this might be a better way, on the side of the pipe rather than inside and in between the pipes, i actually had a straight piece when old mate said he had these and hadn't used them so i grabbed them.

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8 minutes ago, TINGY996 said:

I had looked at a couple of different ways these pipes were done and i decided for ease of manufacture this might be a better way, on the side of the pipe rather than inside and in between the pipes, i actually had a straight piece when old mate said he had these and hadn't used them so i grabbed them.

Probably easier to get the plasma cutter in from the side I would think too, and also the tig/ mig I guess

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