DIY Exhaust Mod – Gain of 10+ HP!!!

[particlewave]

I'm going to go right through the top of the muffler and into the inlet pipe with one or two 1" holes.

Originally Posted by fridsten

I'm considering opening up my muffler, enlarging the holes where the pipes enter, thus making what could pretty much be called an internal Pedro mod.


Drilling by the red arrows would allow the exhausts to follow the blue arrows into the outlet.

Would that work? It would be a fairly easy mod to make, provided you're able to weld or get someone to do it for you. It would also look completely stock from the outside.

[The Radium King]

Originally Posted by particlewave

I'm going to go right through the top of the muffler and into the inlet pipe with one or two 1" holes.

i wonder if you could go in via the entrance pipe to drill the holes - similar to the crios mod?

if you do as you say, perhaps a couple of 3/4" knockout plugs to fill the hole - no welding required, do it while the muffler is in the car?

[particlewave]

Originally Posted by More

Thread needs more pics for us 97 to 99 Boxsters. I need to see where exactly to drill the holes.

I'm not completely convinced that it does anything on the earlier mufflers because of the sound deadening material inside.

Originally Posted by The Radium King

i wonder if you could go in via the entrance pipe to drill the holes - similar to the crios mod?

if you do as you say, perhaps a couple of 3/4" knockout plugs to fill the hole - no welding required, do it while the muffler is in the car?

I will definitely look into this. It will be after the 1st of the year before I get to it. If I can't get at it from the inlet, I'll go through the top (don't want the plugged holes to be visible from the bottom).

[More]

Any 98ers on here that have made this modification?

Does it work?

[particlewave]

Originally Posted by fridsten

I'm considering opening up my muffler, enlarging the holes where the pipes enter, thus making what could pretty much be called an internal Pedro mod.


Drilling by the red arrows would allow the exhausts to follow the blue arrows into the outlet.

Would that work? It would be a fairly easy mod to make, provided you're able to weld or get someone to do it for you. It would also look completely stock from the outside.

Originally Posted by particlewave

I'm going to go right through the top of the muffler and into the inlet pipe with one or two 1" holes.

Internal muffler bypass that does the same as bypass pipes or the Porsche Sport Exhaust.

1" hole drilled in shell and pilot hole drilled into inlet pipe.


Inlet pipe hole widened to 7/8"


I punched through both the top and bottom of the inlet pipes and widened each to 1", so two 1" holes in each.

The cross sectional area of a 1.5" bypass pipe is 1.77".
The cross sectional area of a 1" hole is 0.79", so I have a total of 1.58" per side...very close to the 1.5" bypass pipe.

I'm going to get the shell holes closed up tomorrow and muffler reinstalled, then I'll test it out on Wednesday, so I'll report back then with results.

[fridsten]

Originally Posted by particlewave

I'm going to get the shell holes closed up tomorrow and muffler reinstalled, then I'll test it out on Wednesday, so I'll report back then with results.

Excellent!