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Discussion Starter · #1 ·
I spent some time shopping for a slip on for my 09 GT. Mainly wanted to remove the catalytic converter and I did manage to shave quite a bit of weight off that thing is heavy.
I have Remus on my K 1200 S and this exhaust system is not much different in sound I took the DB killer out it made it a little louder than with it I will give it a test ride tomorrow hopefully and see if it’s OK if my wife is going to ride two up on it I would probably put it back in but she didn’t really enjoy it on the 80 mile test ride I did with her she likes the Road Glide and Grand American better
If anybody is on the fence about a slip on I looked at the GPR and heard one on a K 1200 S the other day I wasn’t too impressed with the sound and how short it was this is an 18 inch Delkevic carbon fiber the fit and finish is beautiful it does not have springs like my Remus it has a nice clamp. See photos
 

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Discussion Starter · #3 ·
I'm looking at the same Delkevic, but not in carbon. How much louder than the stock pipe is it?
The stock pipe was so quiet you only hear the motor not exhaust lol. It’s twice as loud I guess you could say without the DB Killer insert in it's nowhere near Obnoxious
 
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Discussion Starter · #4 ·
Update I rode the bike with the DB killer out on the new Delkevic slip on very happy with it's not loud at all sounds just like I’m riding my K1200S
My buddy that was behind me said when I rolled it on it sounded mean. We did a quick freeway blast for about 25 miles he was behind me on his new 21RT and said it has that sound that says don’t F— with me. Lol.
 

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I have the shorter 14” Delkevic on my K12R and leave the db insert in. Plenty loud enough without being obnoxious. I keep the revs down when leaving my neighborhood to ensure I don’t annoy the neighbors when I leave early for work. Nice pipe, excellent quality, great pipe!
 

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Interesting.

Delkevic are decent value. They used to be badly made/fitting but got a lot better about 4 years ago. I have one on my Honda CB1000R and it works and sounds good.

I fitted a GPR titanium can (the shortish 100mm OD one) and link pipe on my 1300GT and it was very light and sounded great with the baffle (DB killer to you guys) in but far too loud without it. I'll be looking for a longer/fatter can for the GT and using the GPR on the Honda to save weight (the Delkevic is stainless) and for other reasons
 

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Interestingly the full Akra for the 1300S has a large, long carbon can that is straight through and it is still only 99DB - quite acceptable on the road.

Think the current fashion for short/narrow cans is stupid - a long large diameter can has to be the way to go. I've asked various exhaust manufaturers if they can make me a special: straight through, with larger diameter (125mm would be nice) and long (550mm+) but they buy their blanks in pre-cut so can't do it. 110mm diameter and 440mm seems to be the max
 

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Managed to pick this Tri Oval Delkevic up cheap ($20 AUD) as it was missing a bracket, so I made my own until I get the genuine In a week or so. The muffler was only recently repacked. 450mm long with 51mm intake diameter.

Although I also have the titanium Delkevic (350mm) the sound quality of this carbon Tri Oval is much nicer, perhaps because it is 100mm longer.

One thing I found interesting is that Delkevic uses a pipe reducer to 51mm, and was curious if this would possibly have a negative effect on performance.

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Managed to pick this Tri Oval Delkevic up cheap ($20 AUD)...

Although I also have the titanium Delkevic (350mm) the sound quality of this carbon Tri Oval is much nicer, perhaps because it is 100mm longer.

One thing I found interesting is that Delkevic uses a pipe reducer to 51mm, and was curious if this would possibly have a negative effect on performance.
Bit of a bargain. Yeah, as I said above, longer cans are better - they attenuate noise at very little cost compared to fitting a more restrictive baffle. A friend's just had is Aprilia RSV4 dynod and found the stubby Austin Racing and short decat pipe he'd fitted for fashion reasons was costing him power. He put a decent length link pipe and a long Akra can on and gained 15bhp!

Re the 51mm reduction, it depends where it is: if its just the perforated tube that's down to 51mm thats pretty standard to reduce a 60mm pipe to 51 for that - it just forces a bit of gas to go via the wadding, which does cost a little power but kills a lot more noise. If its downstream of that, you've probably got a baffle there anyway (?). If its upstream of that it will reduce flow for no real gain but probably isn't much different in practice to downstream/having a baffle. The old formula used to be that a 2 inch OD pipe was good for a maximum of about 160bhp, a 2.5inch (63mm) OD pipe, good for 220bhp etc, so in theory a 51mm (2 inches near as damn it) restiction limits you to 160,.....but most modern bikes developing way over 160bhp put the exhaust gas through a hole under 51mm at some point, so I'm not sure if the old rule still applies.
 

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Bit of a bargain. Yeah, as I said above, longer cans are better - they attenuate noise at very little cost compared to fitting a more restrictive baffle. A friend's just had is Aprilia RSV4 dynod and found the stubby Austin Racing and short decat pipe he'd fitted for fashion reasons was costing him power. He put a decent length link pipe and a long Akra can on and gained 15bhp!

Re the 51mm reduction, it depends where it is: if its just the perforated tube that's down to 51mm thats pretty standard to reduce a 60mm pipe to 51 for that - it just forces a bit of gas to go via the wadding, which does cost a little power but kills a lot more noise. If its downstream of that, you've probably got a baffle there anyway (?). If its upstream of that it will reduce flow for no real gain but probably isn't much different in practice to downstream/having a baffle. The old formula used to be that a 2 inch OD pipe was good for a maximum of about 160bhp, a 2.5inch (63mm) OD pipe, good for 220bhp etc, so in theory a 51mm (2 inches near as damn it) restiction limits you to 160,.....but most modern bikes developing way over 160bhp put the exhaust gas through a hole under 51mm at some point, so I'm not sure if the old rule still applies.
The restriction I am talking about is the link pipe where it joins the BMW header pipe (where the stock muffler was removed) A picture bellow. I have removed the baffles in both the Titanium Oval and Carbon Tri Oval. The Titanium without a baffle is a bit too loud, and I much prefer the sound of the longer Carbon.

The Delkevic from what I see is just a straight through 51mm pipe (all way through) and dyno results available on Delkevic web shows it increased power and torque so cannot be that restricted.

The genuine BMW stock muffler has a large 65mm intake side, but the outlet (end of the muffler) is only 45mm.

Would be curious to find a muffler that suit the K1300 that has a larger than 51mm diameter all way, but not sure if I would see any improvement.

Compared to the stock muffler both my Delkevic mufflers perform better (especially with baffle out).
 

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The restriction I am talking about is the link pipe where it joins the BMW header pipe (where the stock muffler was removed) A picture bellow. I have removed the baffles in both the Titanium Oval and Carbon Tri Oval. The Titanium without a baffle is a bit too loud, and I much prefer the sound of the longer Carbon.

The Delkevic from what I see is just a straight through 51mm pipe (all way through) and dyno results available on Delkevic web shows it increased power and torque so cannot be that restricted.

The genuine BMW stock muffler has a large 65mm intake side, but the outlet (end of the muffler) is only 45mm.

Would be curious to find a muffler that suit the K1300 that has a larger than 51mm diameter all way, but not sure if I would see any improvement.

Compared to the stock muffler both my Delkevic mufflers perform better (especially with baffle out).
Would assume that restriction before the can would reduce power more than (and additionally to) restricting it at the outlet of of the silencer (as with the standard one) as you ideally need the same (or slightly increasing) section all the way to the beginning of the silencer which is the main resonant length that matters (length to atmosphere also matters but not nearly as much as the length to the first plenum).

A larger diameter muffler all the way through would definitely reduce power less than one with a 51mm perforated section but would be louder - you;d need a much longer can to get the same. I asked an aftermarket exhaust firm this and they confirmed the reduction to 51mm is for this reason.
 
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