BigRedAF said:
Rich I went to the Thunder Alley web site, interesting design.
Are you aware of any comparison data floating around by a third party. The mega phone design has worked well in the past so you have my attention...
I'm always interested in stuff that works.
Bob Murray at Thunder Alley runs a small shop building each pipe by hand, so he doesn't have the money or the juice to get a magazine test. I don't think you'll find the guys making $800 pipes that don't do much of anything comparing themselves to a $250 pipe like the TA that actually works. I think it might be bad for business. ;)
From my own testing the basic 8/32 meg design is the right one for the type of power we are talking about. All the pipes I've made myself over the years have been of similar design, so it was nice to be able to buy one that was already available and incredibly well made.
I don't have any BS dynojet charts to show you. I just did seat of the pants testing on the track with a few riders on my CRF450 and some basic data acquisition studies on the street with timing beacons in Supermoto trim to confirm the seat observations were real.
It's a good design, it works, it's well made, it fits better than the OEM Honda part and it's priced for racers not high profits. Is it the best pipe? Beats me, but I've yet to find or build one that did a better job of filling in the torque curve below the peak torque rpm. This holds true for the CRF and my YZ444F Supermoto. I built a couple of pipes for this bike and even tested with a high dollar Italian Arrow stepped system. The Thunder Alley pipe I borrowed for the YZF felt every bit as strong as the Arrow from an on bike perspective, but the Arrow pipe was much quieter so it got the nod for street riding.
The downsides :
- the TA meg portion is mild steel so it has to be maintained or ceramic coated. Mine is non-coated, but gets the scotchbrite and WD40 treatment now and then. The muffler is aluminum so it's no trouble.
- the very nature of how a meg performs it's wave tuning magic makes this pipe very loud. Bob has some quiet inserts but I've never tested them. It is probably too loud for areas that are noise sensitive, but that holds true for most of the pipes I've seen that make any power. The few quiet pipes like the FMF Q just kill the response of the engine. Single absorption style mufflers are not likely to be the long term answer for making good power and keeping quiet.
I am still running the same TA pipe on my CRF450 Supermoto bike that I bought 5 years ago, and it still looks good, and performs like a champ.
On top of it all Bob Murray is one of the genuine nice guys in the motorcycle business who really goes the mile for his customers.
Here's a little review I wrote on the pipe when I first started testing them on my CRF450.
http://www.dirtrider.net/forums3/showthread.php?t=53760&highlight=thunder+alley
I hope this helps.