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Discussion Starter · #1 ·
Hi guys & gals. Ok this time I did a search to see if this has been discussed before, I'm sure it has been but I couldn't find any threads, so here goes.

It seems to me that muffler slip ons and full exhaust systems are a heck of a lot of money. Do you really get that much more horsepower from a slipon or complete exhaust system versus just pulling out the silencer? It seems to me that without the silencer, the stock muffler would flow pretty well. I have already converted to a K&N filter with larger intake and a PCIII that I can download a map for those two mods and my exhaust with out the silencer. Am I missing out on a bunch of ponies? Thanks for your time, I really enjoy this forum and have learned alot already.
 

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Yes it is true that the stock exhaust does flow better w/out the spark arrestor in. However, aftermarket exhaust companies have done
a much better job with the pipe bends and pipe diameter to increase exhaust flow and performance. I don't know exact HP numbers but
I know personally that it made a huge differance on my 700 with the full HMF exhaust vs. stock with the sparky removed. I would spend the extra money to get an aftermarket exhaust. There are a ton to choose from. I went with the full HMF sport because I read in a lot of magazines that it made the most power ans sounds great. Plus differnt colors for the muffler look awsome. :thumbsup:
If you've got razorblades in your pocket book, then stick with stock exhaust but in the long run you are not getting the performance
potential.
 

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Well with my experience it's not just the cork in the end. It's the header design and size. The factory cans are all chambered and baffled. I have taken on other quads and just hulled out the can and fabbed up a race core and packing just like a slip on with good results. On a 700 V force one of my factory modded cans made 5 hp over stock on a dyno. It's still not as good as you can get from a good complete exhaust system because the header doesn't flow as well. 8)

sorry got beat to the draw.
 

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Guys it sounds like to me hes talking more about compairing a stock muffler with the silancer removed compaired to a slip-on. This should take all the bends and such out of the picture (compaired to if it was a full exhaust), since a slip on really dont have any big bends in it. I would be curious to see what a GYTR slip on and stock pipe with the baffle removed would do on a dyno. I bet it not that far off. Maybe 1-2 hp if that. What do you guys think?
 

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Yea your probalby right. theres probably not a whole of diff btween a slip on and the stocker uncorked. Right now I'm waiting on my DMCs to get here and thats what I'm running but with my map set to the duals so I'm a little rich. But it still hauls a$$. sounds pissed too. :thumbsup:
 

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The stock muffler with baffle removed almost makes it just a straight through pipe. If I were you, I would buy a Power Commander 3 programmer and run your rappy with baffle removed and air lid box off. That would cost you $250 from fuelmoto I believe. You should expect about a 5hp gain for sure! with just that.

p.s., if you ever do mods later, you just change the setting on the Power commander :thumbsup:
 

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Rapt0rMan said:
If you took the baffle out woldn't you lose a lot of the back pressure?

Alot of us have duel exhausts with little back pressure, as long has you have your air/fuel ratios correct with a programmer you are perfectly fine! :thumbsup:
 

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Machy said:
The stock muffler with baffle removed almost makes it just a straight through pipe. If I were you, I would buy a Power Commander 3 programmer and run your rappy with baffle removed and air lid box off. That would cost you $250 from fuelmoto I believe. You should expect about a 5hp gain for sure! with just that.

p.s., if you ever do mods later, you just change the setting on the Power commander :thumbsup:
I agree. I bet you can get a good 6-10hp with intake, baffle removed, and pcIII. I would really like to see dyno numbers.
 

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Back pressure is really only an issue when you have a cam with a lot of overlap... the stock cams in these things are so mild, back pressure is useless. Later on, as you add cams, and a free flowing exhaust, the lack of backpressure might hurt the very very low-end torque (just off idle) but other than that, it's all gain. (Nobody with those kind of mods putts around at 2,000 rpm anyway!) :thumbsup:
 

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Discussion Starter · #11 ·
Thanks everyone for your comments. The information is trully appreciated. I have the K&N filter and PCIII, so with the spark arrester removed and the right map downloaded, I guess I am making as many ponies as possible for my current budget.I can really feel the difference from straight stock, hope to see you on the trails! Again, thanks to all who responded!
 

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From yamaha's web: Yamaha GYTR™ Performance Oval Muffler

Offers 16% increase in low-to-midrange horsepower, a 3.8 peak horsepower gain and up to 30% more power after peak when used with the GYTR High Flow Air Filter (GYT-1S395-01-00). 2.5 lbs. lighter than stock.

Now that does not include a PC III. Stock muffler is a chamber muffler, there is no packing that i can find like slip ons. A slip on is a straight through design with a silencing material inside that has to be changed every eight hours, depending on how one rides.
Now for the head pipe, performance exhaust and GYTR filter they claim:

This stainless steel performance header, combined with the GYTR Performance Oval Muffler, will add 20% increase to mid-range horsepower and a 4.3 peak horsepower gain when used with the GYTR High Flow Air Filter (GYT-1S395-01-00).

There really is not a whole lot of difference between using a slip on and a full system. Add a Power Commander and maybe 3-6 more HP for a total of 6-10 HP
 
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