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Discussion Starter · #1 ·
Hi all. I took the great advise from everyone on here and drilled the exhaust on my 2004 VRSCA. I added (8) 7/16" holes, evenly spaced, on each muffler end. It was easy to accomplish and the sound is great. The question is: Should there be any change to the performance or gas mileage? It seems, and I stress "seems" that the acceleration isnt quite what it was and the gas mileage seems to have dropped off. Riding conservatively, getting into 5th by 50 mph, I used to get close to 50mpg. Now, its seems have dropped off to closer to 40mpg. Althought the bike is still fast, its doesnt seem to accelerate as smooth or quickly as it did before the drilling. Is it perception or an outcome of the changed exhaust? Any feedback or info would be appreciated. Either way, I still LOVE my VROD!!! Thanks:moped:
 

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Blowin' Smoke
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You have probably gone a bit large with the holes, and now the bike is running somewhat lean. If your power loss seems to show up in the mid range this is certainly the case. A fuel tuner like the Power Commander or a Techlusion box is probably in order. I use a Gil's box on mine and have had good luck with it.

These motors are pretty finely tuned from the factory, and you have reduced the back pressure, which allows more air flow. It seems like an oxymoron that less back pressure, more air flow, etc. results in decreased fuel mileage and reduced performance, but that is exactly what happens. You would probably have been fine with somewhat smaller holes or fewer holes, but that's hard to know for each bike before you start.
 

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THAWING In Montana
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I drilled 8 3/8" holes in mine, and I think it may be slightly less power...It could be my imagination though.
 

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FireBum
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485 Posts
I have 8, 1/2 inch holes in one set of pipes, v-mod pipes, and stock pipes. I have the pipe change down to 4 minutes so I change them all the time.

Between the drilled and stock pipes the drilled are faster from mid to high rpm but the stock pipes have greater torque from a stop through about 4000 rpm. When I was running the stock Dunlop and drilled pipes the tire would break loose at about 6500 rpm and spin till the rev limiter stopped it. With the stock pipes it would spin earlier and stop on its own.

The stock pipes make it faster in cold weather and the drilled are faster when its hot out.

All around I dig the drilled for the performance and retaining the looks of the stock pipes. My fuel milage ranges from 32 to 47 depending on who I ride with. I'd say I average about 40.:blahblah:
 

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Discussion Starter · #5 ·
Thanks everyone for the info. I think I'm going to get a set of undrilled stocks just have on hand. Great idea Shonoff. They are just too quiet to leave on all the time!
 

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For me i purchased force pipes with no baffles.That killed my torque totaly.There is a fine line between sound and performance.What helped me was i kept the pipes and added baffles from thunder monster right before the mixing chamber.That gave me back pressure and my torque back.And the bike sounds great now .I love the bike now.
 

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Premium Member
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you will lose a little midrange as in practice you have lost a little back pressure .
what you have done by drilling the exhaust is shorten the route of the gasses throught he pipe.thus affecting the resonance of the pipes.
i drilled my stockers and did not notice a drop in MPG.
perhaps you are going faster ???

remember this is a low price mod to get better sound, if you require better performance/ mpg then a pukka pipe (se,v+h,cfr etc) will be needed.
 

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The Engineer
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Methinks if your MPG has dropped it's because you like the sound and exercise the right hand a bit more than you did before. :)

If anything you'd notice a barely tangible increase since it would be ever so slightly leaner and use less fuel than before.

I picked up my R from the 1000-mile cornholing yesterday afternoon and popped eight 1/2" holes in each can last night. Made no discernable difference in performance, and sounds better than my Craftsman lawn tractor now. And, curiously, I don't have the occasional funny stumble at highway speeds now that it did before.....

Until I can swing some Supertrapp FatShot slip-ons and a PC3 I'm happy.
 

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Smokin some asphalt!
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Get a Thunderheader and be done with it!!!:D
 

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50 mpg? Are you serious? Even bone stock I didnt get anywhere near that. That is my main complaint about the vrsc is the sucky gas mileage. Anytime you change your exhaust it will change the way your bike runs. Sometimes to the better, sometimes to the worse. Get a power commander (or something) and dial it back in. Sounds like ur off a little bit.
 
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