I have a ThunderHeader 2:1 system currently and was planning on changing to a SuperTrapp 2:1 system to get a less noise on my Road King. I think from what I've read hear that the performance is about the same, I'm looking for low end torque. My bud told me today that he had 12 spacers in his SuperTrapp and it made as much noise as my ThunderHeader. So before I waste another $700 on the SuperTrapp is he right or just full of BS? Really want to quite this thing down and get low end Torque.

 

Might want to check out the Hacker Warheader as well. Just got mine, not installed yet. Have you alson thought of changing out your cam for more Low End? Probably your best bet, or possibly your compensating sprocket gear.

 

You probably know that the ST and TH are consistently 2 of the top rated power pipes the past 25 or more years.

the supertrapp can be loud with an open end cap or quieted down with a closed end cap and adding more discs in the stack ( more on this below)

Typically the "core" is 2" in diameter- about 28 discs equals the flow through this 2" core.

the core is perforated with packing on the outside, it is important that this packing stay in place, otherwise gases can loose velocity and direction resulting in a reduced net flow.

the "closed course" open end cap is equal to about 10 discs for tuning purposes, the nightstick open end cap is slightly smaller opening equal to about 9 discs.


when discs are stacked, in profile the gasses are forced through a "W" shaped passage ( 360º around) the W actually changes size which retains gas velocity and breaks up sound waves in the higher frequencies ( the packing is absorbing the low frequencies).

the more discs, more more net flow, less restriction and more noise--- and an emphasis on HP

the fewer discs ( with in a range) less flow, slightly more restriction and an emphasis on torque.

ST has tuning guides generally on a TC start at 18 or 20 discs and a closed cap, then go up or down 3 discs at a time, observing the changes- and dialing in the right combo for your motor, bike gearing and riding style.


when going on an extended road trip I usually add a couple of discs for a little more HP as I will be about 3000 rpms 99% of the riding day.


what i do:

built hipo 80" FXRP ST 2/1 closed cap 22 discs ( this lightweight bike has a 15% overdrive so I am tuned for torque to overcome the overdrive in town.)

stage 1 80" FLHTC w stock headers ST slip ons 14 discs rt side, 6 or 7 left side, closed caps

stage 1 09 FLHTC 96" stock header ST slip ons 16 rt/ 9 left closed cap.

recently replaced with take off nightsticks on the stock headers, same disc count, but running dummy discs on the left side ( so pipes are the same length) and closed caps up inside the open nightstick caps.

the volume of the bagger header system ( no cat) is itself an advantage for torque, and I am fine with the stock headers as the bagger motors i leave at stage 1.




mike

 

depends on with end cap also,right now I've got 9 discs open cap,about as loud as 2"" rush slip on,14 and open end cap too loud for me,16-20 with closed end cap goes from almost stock to a tame screaming eagle.ive had 14- 25 discs with closed cap but the sound was just a little muffled for me i like fewer discs with open cap gives a deeper pitch.

 

i also was able to pull a lot of fuel out of the decel and picked up a few mpg,these st seem to be less prone to popping.

 

Won't be using the open end cap as I'm feed up with the noise.

 

I just put a SuperMeg on a couple of weeks ago and my passenger is experiencing too much heat on her right foot. The bike has been dyno tuned following the SuperMeg install. I'm curious if anyone else has experienced this with the SuperMeg?

 

Im running 28 discs on my 103 and love the hell out of it, can ride 10 hours a day for 10 days straight and dont end up deaf. Also am pulling respectable hp/tq numbers.

 

I have a Supermeg, with closed end cap and all the discs that came with it. No heat problems. Excellent torque, plus my motor runs very smooth and sweet. I had TDs previously and the improvement is wonderful! I haven't tried any of the other 2-into-1s because of their reputation for making noise. I ride to enjoy the experience, not to annoy the neighbours!