Basically, I wanted a lighter-weight exhaust option - mainly getting the weight from under the tail....I found only 2 options from my research. I read mixed reviews about Coffman's without any data back-up. So I decided to do my own data....
The unit - I received an extremely well packaged slip on in a very quick timeframe. The unit is xx long by xx round. The unit has a very nice powder coated finish on a steel body and you can choose different color aluminum tips to add a customized look. The unit also comes with a removable silencer (you can remove by a well designed lock-ring) in case you want it a little quieter. Inside the can, there is a small layer of packing held in place by a welded mesh metal which is replaceable by taking off the tip (3 allen bolts) to help keep the noise down.
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Weight - The unit only weighs 2.275lbs withOUT silencer but WITH the mounting clamp! With silencer and mounting clamp, the unit weighs 2.5lbs. Putting this exhaust on, I weighed everything I was able to take off the bike exhaust wise....here is the list:
Twin GYTR carbon slip ons - 9.89 lbs
M4 mid-pipe - 3.27 lbs
3 carbon heat shields - .26 lbs
nuts, bolts, brackets - .25
Total weight savings - 11.395 lbs! (13.67 total, add back 2.275 for the Coffman's) Keep in mind, this is almost 10lbs of up-high weight! (this will drastically affect the handling - making the bike feel lighter when flicking side to side).
Dyno time! - Honestly, I didn't go to the dyno with the highest of hopes....BUT! I was pleasantly surprised by the numbers! I only dropped 2.34hp but gained 1.2 ft/lbs of torque!
My Original Map With GYTR/M4 Midpipe/BMC filter/Flash/PCV
Coffman Slip on/BMC filter/Flash/PCV
Red line - without silencer
Blue line - with silencer
![Image]()
As you can see, the curve isn't the smoothest out there, but that's the trade off for getting the bike to handle better. I was told I may or may not feel the dips, but that is for review part 2 coming in the end of May when I get to the track....
Also, notice the blue line...that is running the bike WITH silencer. Unfortunately, you really don't want to do that. lol. The last huge dip then spike is where the bike actually blew the pipe off the bike! (The Coffman exhaust comes with a very small pin attached. You should drill a hole in the header and USE THE PIN! lol. This will stop the exhaust from blowing off if it's not tight enough or spinning over time. If you go back to a midpipe, this small hole will NOT affect anything on the header since it is underneath the exhaust gasket)
Disclaimer - If you run this exhaust, you MUST get it re-mapped. The first few pulls were pretty ugly, mostly running rich, down about 8hp.
Sound - Unfortunately, I don't have a professional sound meter, so I used a well-reviewed iphone app. With silencer, I measured (outside, in an open area) 92db at idle, 101db at 12,000 rpm. Without silencer, 94db at idle, 102 db at 12,000 rpm. For reference, another company's low mount measures "over 105db at 8,000 rpm" (quoted from the manufacturer). So if you like loud, you won't mind the sound. If you're looking for something more quiet, this isn't for you. Without the silencer, it has a deep, grumbling tone...I don't mind it. And if you're going to a track, please check with the track by-laws.
So, in closing, I did this test to give us data about an exhaust that has been talked about but never really discussed at length. I tried to keep it as factual as possible with numbers and dyno sheets. Any feedback is appreciated.
My opinion time - I am pleasantly surprised so far by this little gem. It's loud, but not obnoxious. I haven't ridden it yet (its been a LONG winter in New England), but am looking forward to the handling changes. I will be doing a part 2 at the end of May. 1 section will be street, 1 track (a track I've been to a handful of times with the undertail exhaust). My only real concern is the volume. But after finding out the other guys are over 105db's, this is actually a quieter alternative. We'll see how that transfers to the street though since I like going on early morning cruises. I posted up over on WERA about the volume, and everyone basically said, for the track, that's not that bad and I shouldn't be concerned at all about it.
I can't say enough about Gary and Pam Coffman either. They've been very supportive and responsive throughout the process and actually care very much about the results, their product and their company. I would not hesitate to buy from them for the my bike or my car....
Okay....Did some 'real world' testing. 1st test was commuting to work....68 miles round trip all highway. Did this a couple of times. I noticed absolutely NO difference except the volume. Cruised at about 5500-6000 RPMs. No noticed MPG difference either. Power was still there when needed, and also the smoothness of the delivery.
2nd test was a day at the new Thompson Motor Speedway in Thompson, CT. It's a smaller, tight track with a long, fast front straight. 1st off - the weight savings put a grin on my face ear to ear! It turned in so much easier and was so much LESS a struggle to get it moving side to side.....It's everything I was hoping and then some! As for the power delivery.....I didn't notice anything different (which I am more than pleased about). THe nice thing about the track - I was mostly in 2nd and 3rd all through the rpm range. The power was there when needed and I felt no sluggishness or the dips where the chart says I should have them. A couple teammates that have ridden the bike with the undertail exhaust both commented on how much easier the bike was to throw around, stay in line, finish the corner AND how much LESS work it was to be out there for an entire session.
Over all, I am extremely pleased with my Coffman's Exhaust. For a trackday rider and double duty bike, I am overall happy I put the time in....It's definitely worth it!
Thanks again to Pam and Gary Coffman with there great product, great prices and SUPER customer service!
The unit - I received an extremely well packaged slip on in a very quick timeframe. The unit is xx long by xx round. The unit has a very nice powder coated finish on a steel body and you can choose different color aluminum tips to add a customized look. The unit also comes with a removable silencer (you can remove by a well designed lock-ring) in case you want it a little quieter. Inside the can, there is a small layer of packing held in place by a welded mesh metal which is replaceable by taking off the tip (3 allen bolts) to help keep the noise down.
Weight - The unit only weighs 2.275lbs withOUT silencer but WITH the mounting clamp! With silencer and mounting clamp, the unit weighs 2.5lbs. Putting this exhaust on, I weighed everything I was able to take off the bike exhaust wise....here is the list:
Twin GYTR carbon slip ons - 9.89 lbs
M4 mid-pipe - 3.27 lbs
3 carbon heat shields - .26 lbs
nuts, bolts, brackets - .25
Total weight savings - 11.395 lbs! (13.67 total, add back 2.275 for the Coffman's) Keep in mind, this is almost 10lbs of up-high weight! (this will drastically affect the handling - making the bike feel lighter when flicking side to side).
Dyno time! - Honestly, I didn't go to the dyno with the highest of hopes....BUT! I was pleasantly surprised by the numbers! I only dropped 2.34hp but gained 1.2 ft/lbs of torque!
My Original Map With GYTR/M4 Midpipe/BMC filter/Flash/PCV
Coffman Slip on/BMC filter/Flash/PCV
Red line - without silencer
Blue line - with silencer
As you can see, the curve isn't the smoothest out there, but that's the trade off for getting the bike to handle better. I was told I may or may not feel the dips, but that is for review part 2 coming in the end of May when I get to the track....
Also, notice the blue line...that is running the bike WITH silencer. Unfortunately, you really don't want to do that. lol. The last huge dip then spike is where the bike actually blew the pipe off the bike! (The Coffman exhaust comes with a very small pin attached. You should drill a hole in the header and USE THE PIN! lol. This will stop the exhaust from blowing off if it's not tight enough or spinning over time. If you go back to a midpipe, this small hole will NOT affect anything on the header since it is underneath the exhaust gasket)
Disclaimer - If you run this exhaust, you MUST get it re-mapped. The first few pulls were pretty ugly, mostly running rich, down about 8hp.
Sound - Unfortunately, I don't have a professional sound meter, so I used a well-reviewed iphone app. With silencer, I measured (outside, in an open area) 92db at idle, 101db at 12,000 rpm. Without silencer, 94db at idle, 102 db at 12,000 rpm. For reference, another company's low mount measures "over 105db at 8,000 rpm" (quoted from the manufacturer). So if you like loud, you won't mind the sound. If you're looking for something more quiet, this isn't for you. Without the silencer, it has a deep, grumbling tone...I don't mind it. And if you're going to a track, please check with the track by-laws.
So, in closing, I did this test to give us data about an exhaust that has been talked about but never really discussed at length. I tried to keep it as factual as possible with numbers and dyno sheets. Any feedback is appreciated.
My opinion time - I am pleasantly surprised so far by this little gem. It's loud, but not obnoxious. I haven't ridden it yet (its been a LONG winter in New England), but am looking forward to the handling changes. I will be doing a part 2 at the end of May. 1 section will be street, 1 track (a track I've been to a handful of times with the undertail exhaust). My only real concern is the volume. But after finding out the other guys are over 105db's, this is actually a quieter alternative. We'll see how that transfers to the street though since I like going on early morning cruises. I posted up over on WERA about the volume, and everyone basically said, for the track, that's not that bad and I shouldn't be concerned at all about it.
I can't say enough about Gary and Pam Coffman either. They've been very supportive and responsive throughout the process and actually care very much about the results, their product and their company. I would not hesitate to buy from them for the my bike or my car....
Okay....Did some 'real world' testing. 1st test was commuting to work....68 miles round trip all highway. Did this a couple of times. I noticed absolutely NO difference except the volume. Cruised at about 5500-6000 RPMs. No noticed MPG difference either. Power was still there when needed, and also the smoothness of the delivery.
2nd test was a day at the new Thompson Motor Speedway in Thompson, CT. It's a smaller, tight track with a long, fast front straight. 1st off - the weight savings put a grin on my face ear to ear! It turned in so much easier and was so much LESS a struggle to get it moving side to side.....It's everything I was hoping and then some! As for the power delivery.....I didn't notice anything different (which I am more than pleased about). THe nice thing about the track - I was mostly in 2nd and 3rd all through the rpm range. The power was there when needed and I felt no sluggishness or the dips where the chart says I should have them. A couple teammates that have ridden the bike with the undertail exhaust both commented on how much easier the bike was to throw around, stay in line, finish the corner AND how much LESS work it was to be out there for an entire session.
Over all, I am extremely pleased with my Coffman's Exhaust. For a trackday rider and double duty bike, I am overall happy I put the time in....It's definitely worth it!
Thanks again to Pam and Gary Coffman with there great product, great prices and SUPER customer service!
