This is not a ride report about the most powerful pipe for a ds but it is something that quite a few ds riders have been waiting for so i thought i would share my thoughts on its performance.I installed the HMF QS1 and right away i was impressed with the fit and finish but the performance is very good for a quiet pipe also.I jetted my carb with a 175 mikuni main and i left all other settings as they were stock and i put (8) 1"holes in my airbox lid and used uni vents to plug the holes along with a K&N filter and the gains i got although not incredible were noticeable and throttle response was greatly improved.I should add that i also use a big gun cdi and that helps but the gains with the pipe were good all on their own and according to HMF the decibel level should be below 96 and with what i heard today i think that it is at least that quiet. If you are looking for a quiet pipe for your DS as i was i think you would be pleased with the quality and performance of the QS1.

 

Thanks for the report. This is definately what I have been looking for. Is this a slip on of full system? Also do you know if it is USFS spark arrestor approved?

 

Thanks that is just what I have been looking for. What is the price tag.

 

DSengineer-I have the slip on but i think that you can get a full system as well.This also a USFS approved pipe.I wasnt sure if anyone would be interested in a pipe like this but on the oregon dunes where i ride if they choose to be the sound cops can really put it to you with a fine and i didnt want to have to worry about that with my main duning quad. I am pretty sure that the price was 289.00 but because i signed up to there forum i was given a discount of 20.00 so that seems pretty fair to me.

 

We need to get one of these over to MrHP to dyno test against the old HMF slip-on.

 

Great Idea!
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I went over the the HMF site and was able to come up with the following claims according to HMF

- QS1 retains 80% of HP gains compared to the Sport series.
- Sport series 104-105dB without quiet core. ~96dB with QC
- QS1 ~96dB

I e-mailed them to get a HP/flow comparison between the Sport w/QC compared to the QS1. I will let you know what I find out.

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Do you know if Eric has ever dyno'd the Sport series with QC installed. I have heard it is pretty restrictive. Hopefully the QS1 is more effecient in reducing dB's.

 

No, just the standard HMF. The quiet core does look to be very restrictive.

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I dont think that the gains with this pipe will be too great(on paper) but to me just the throttle response improvement was worth it.222-The quiet core deos look to be quite a restrictor and in fact i may slightly enlarge the small hole in the restrictor gradually while keeping and eye on performance and making sure to not get too loud.I think that there may be some gains to be had by increasing the size of the outlet hole on the internal restrictor while still maintaining a lower decibel level than most .

 

A forum member has ordered one and is allowing us to dyno it before we ship it out. So, we should have some answers soon.
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