Thunder Alley Power Band Increases?

I was curious what the Thunder Alley users thought of their power band with the new muffler. I noticed a big increase in low end and mid range but not a change in top end or even a possible decrease in top end.

I did change to the larger main that they suggested so I think the jetting is close.



I noticed a big increase in low to mid also. I think I did lose a slight bit of top end power. The only time I noticed it is when I was goofing around and doing high speed runs on a paved road. Maybe it is not a power loss, but a different feel.

On the track the power feels much better with the TA. I also run a 168 main as recomended.

My bike just flat out rips after the Thunder Alley was installed . It revved and revved and revved . I felt a change throughout the power band . Fekt like I bolted on a supercharger. Thats my opinion . I cant wait for the ceramic coating . It should help my bike out alot . Imagine how much heat comes off that headpipe, how it glows at night. Imagine how much better it has to run when the exhaust gasses are flowing out of the exhaust pipe the way they should . This is the best performance mod I have done .But all things aside . I am no pro , I could use alot more seat time . Becouse I cannot ride my bike to its potential. This is just Hopping on a gravel road and opening it up test . No racing on a track was performed . But Holy Cow ! this bike really gave my bike grunt coming out of corners. MY final opinion ( WOW ) :)

MX974, My dyno runs confirmed a good increase in the bottom / mid with a loss at the top end..

Thanks for the feedback guys! Jon, do you have any numbers on your dyno run like hp increases on low and mid range and how much was lost on top end?

The Thunder Alley might be the best choice for a tight MX track or tight woods and something else for a fast track.

It works perfect for me. I love the extra low end power. I am more of a lugger. When the berms are in good shape, I sometimes put my bike in third gear and leave it there. The power out of turns is great, even with stock gearing. The extra low end allows you to do a lot less shifting.

The TA pipe gave more power below 5,500 rpm, with the biggest gain at around 4,500 where it was ~4hp up on the stock pipe. It went flat at 7,000 rpm, losing ~2hp to the stock pipe by 9,000.

Please bear in mind that my engine is a long way from standard, so my figures might not be fully representative of a stock motor.

HTH, Jon E.

Based on this feedback I practiced last Wednesday and shifted earlier and used a taller gear in the corners and wow, I guess it was user error and I was over-reving. I did try my White brothers muffler and it did seem like it had more top end but a lot less low end. I know like the low end, makes it easier to do the doubles out of the tight turns!

Thanks guys! I qualified a to go to Loretta Lynns's in the +45 class so this will be a big help for me there!


Jay you might want to spend some time dailing in the main jet, because my T/A seemed to increase the bottom like everybody else, but the top is never ending. It revs to the moon!

Might be a bike to bike thing, but, thats what I noticed the most really.

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