Knocking out the Cats on 4" mufflers
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RE: Knocking out the Cats on 4" mufflers
Yes, I did this to a pair of '06 CVO pipes.
I was able to pound/bore through the cats (the catsare a soft aluminum type screenmaterial about 1.5" thick) using a 1.5" diametergalvanized pipe (make sure it fits into the muffler inlet and the pipe is not real thick walled). I cutthe pipe at a 90 degree angle toabout 18' long. Thenwith a bench grinder,sharpened the end of the pipe, real sharp. On the other endof the pipe Idrilled two 1/2" holes across from each otherandpushed through, and bolted down, a 12" longbolt to form a "T" handle. Once completed, I put the muffler on the gound with the inlet side facing up. Make sure you use some thick carpet or paddingas a cusion for the outlet end. I inserted the sharp end of the pipe into the inlet (this is where the cat screen is) I used small sledge hammer to pound into the cat material. I periodically sprayed in WD40 to provide lubrication. Every few pounds I use the "T" handle to twist around the pipe so it didn't get lodged into the material. After about 5 minutes or so of pounding and spinning I broke through the material. Since I had been makeing sure the pipe wasn't lodged in the material,I was able to pull out a perfect "plug" of cat material. Once out, there was a perfect, clean 1.75 (approx) hole straight thourgh the cats.
Once done, I was very pleased with the performance and sound of the muffler. It was a little bit louder than before with a nice growl when ramping up. Louder than stock but quieter than V & H or Reinharts.
I was able to pound/bore through the cats (the catsare a soft aluminum type screenmaterial about 1.5" thick) using a 1.5" diametergalvanized pipe (make sure it fits into the muffler inlet and the pipe is not real thick walled). I cutthe pipe at a 90 degree angle toabout 18' long. Thenwith a bench grinder,sharpened the end of the pipe, real sharp. On the other endof the pipe Idrilled two 1/2" holes across from each otherandpushed through, and bolted down, a 12" longbolt to form a "T" handle. Once completed, I put the muffler on the gound with the inlet side facing up. Make sure you use some thick carpet or paddingas a cusion for the outlet end. I inserted the sharp end of the pipe into the inlet (this is where the cat screen is) I used small sledge hammer to pound into the cat material. I periodically sprayed in WD40 to provide lubrication. Every few pounds I use the "T" handle to twist around the pipe so it didn't get lodged into the material. After about 5 minutes or so of pounding and spinning I broke through the material. Since I had been makeing sure the pipe wasn't lodged in the material,I was able to pull out a perfect "plug" of cat material. Once out, there was a perfect, clean 1.75 (approx) hole straight thourgh the cats.
Once done, I was very pleased with the performance and sound of the muffler. It was a little bit louder than before with a nice growl when ramping up. Louder than stock but quieter than V & H or Reinharts.
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Join Date: Oct 2006
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RE: Knocking out the Cats on 4" mufflers
ORIGINAL: Pumba11
Why is that?
Removing the cat "restriction", and what is left is a fully baffled 4" muffler.
Why is that?
Removing the cat "restriction", and what is left is a fully baffled 4" muffler.
#9
RE: Knocking out the Cats on 4" mufflers
Most aftermarket slip-ons reduce the crazy amount of restrictionthe the stock HD muffler has on our bikes. That is why most people get rid of stock mufflers to improve flow and increase tq and hp. I completely understand what backpressure does and that it is needed.
However, on this particular muffler that had an nicely baffled muffler that provides some back pressure, PLUS a flow choaking cat in each muffler was overkill. Removal of the cat eliminated "some" of the backpressure. It is by no means a drag pipe. It would in my opinion still provide more backpressure than most every V&H, Python, Wild Pig, Reinhart yada yada yada slip on muffler out there.
Just my $0.02
However, on this particular muffler that had an nicely baffled muffler that provides some back pressure, PLUS a flow choaking cat in each muffler was overkill. Removal of the cat eliminated "some" of the backpressure. It is by no means a drag pipe. It would in my opinion still provide more backpressure than most every V&H, Python, Wild Pig, Reinhart yada yada yada slip on muffler out there.
Just my $0.02
#10
RE: Knocking out the Cats on 4" mufflers
ORIGINAL: Pumba11
Most aftermarket slip-ons reduce the crazy amount of restrictionthe the stock HD muffler has on our bikes. That is why most people get rid of stock mufflers to improve flow and increase tq and hp. I completely understand what backpressure does and that it is needed.
However, on this particular muffler that had an nicely baffled muffler that provides some back pressure, PLUS a flow choaking cat in each muffler was overkill. Removal of the cat eliminated "some" of the backpressure. It is by no means a drag pipe. It would in my opinion still provide more backpressure than most every V&H, Python, Wild Pig, Reinhart yada yada yada slip on muffler out there.
Just my $0.02
Most aftermarket slip-ons reduce the crazy amount of restrictionthe the stock HD muffler has on our bikes. That is why most people get rid of stock mufflers to improve flow and increase tq and hp. I completely understand what backpressure does and that it is needed.
However, on this particular muffler that had an nicely baffled muffler that provides some back pressure, PLUS a flow choaking cat in each muffler was overkill. Removal of the cat eliminated "some" of the backpressure. It is by no means a drag pipe. It would in my opinion still provide more backpressure than most every V&H, Python, Wild Pig, Reinhart yada yada yada slip on muffler out there.
Just my $0.02
I gutted my stockmuffler and then welded pipe straight threw the center, "like a drag pipe". Performance was increased after converting my stock pipe into a 2-1 pipe. One would think the open pipe would only create power on the "top end" much like a drag pipe but, no. I think the difference is when making my header into a 2-1 there was restriction created where the two pipes meet making backpreasure. What I am saying is you never know till you try it....