I don't have a decibel meter. Even if I did, I'm not gonna re-install all these combinations to get measurements <img src="
https://www.fjrforum.com/forum//public/style_emoticons/<#EMO_DIR#>/smile.gif" style="vertical-align:middle" emoid="
" border="0" alt="smile.gif" />
As for power:
<ul><li>There have been reports of the Holeshot header + stock slip-ons causing a loss in torque across the RPM range. Someone posted a dyno chart as evidence, but I don't remember where or how big the difference was.</li><li>Holeshot claims ~7hp gain with their full system (using the Holeshot slip-ons), but I've never seen a dyno chart of a full Holeshot system compared to stock.</li><li>Here's <a href="
https://www.fjrforum.com/forum//index.php?showtopic=120164" target="_blank">a dyno comparison of my full Holeshot + Remus system compared to stock</a>. Keep in mind that I also had a heavily modified air box at the time (and that my air filter was over-oiled). Also keep in mind that even though there was not a gain in peak HP or torque, this torque curve <a href="
https://www.fjrforum.com/forum//index.php?showtopic=119023" target="_blank">increased overall acceleration significantly</a>, thanks to the relatively high and flat torque curve from 4000-8000 RPM.</li><li>Based on my recent switch from Holeshot to stock header, it appears that the Holeshot header was partially (but not completely) responsible for the decrease in torque below 3700 RPM and the increase from 3700-5200 RPM. I believe the modified air box also contributes to that reassignment of torque (see also <a href="
https://www.fjrforum.com/forum//index.php?showtopic=102302" target="_blank">Wicked Webby's air box mod results</a>, which are inconclusive for the below-3700-RPM area). </li><li>Still nothing conclusive about what caused the slight loss of torque from 6000-8000 RPM. One theory is the over-oiled air filter. Or maybe that's just the result of the Holeshot Header and Remus Hexacones interacting. </li><li>Stock vs K&N air filter is probably insignificant for this bike. The difference between the PCIII fuel maps for the two on a stock bike is very small.</li><li>PCIII or some other fuel tuning system with appropriate tuning/mapping is a must for a full exhaust system. Otherwise, it's still very nice for smoothing out partial throttle hesitation, etc.</li></ul>
The reason I switched back to a stock header was to see if it affected vibration. It didn't. I don't feel like going through all that work again, and I think I like the sound better with the stock header, so be on the lookout for a stainless steel + ceramic coated Holeshot header with an O2 sensor bung in the "for sale" section.