Well, depending on which SE mufflers you have (there are many check for a part number) they are already more free flowing than stock and made for additional torque. Drilling them you would only lose power and they would likely sound like crap.

My SE 65115-98B mufflers provide a really good increase in torque over stock and have worked very good in the mountains.

But my biggest suggestion for two-up mountain riding is to invest in an Andrews 21 or similar cam (SE 255) to boost torgue. I did it this past spring and rode the Rockies with fantastic results. Pulls like a freaking locomotive compared to the stock cam.

Nice bike, enjoy it.

A non-CA '04 bike should not have cats.

 

I had to leave town un-expectedly ... just got back.
Air Cleaner is the Stage I.
I think I can now say that since I first got involved with int. combustion engines I have been modifying them. I start out slow and do my own work learning my way forward. Induction, exhaust improvments lead to com swaps, these projects are generally my gateway to bigger projects.
I really like the thought of the Andrews cam you wrote about and ultimately will migrate in that direction. I like that the cam profile drops the power-band into the lower rpm range.
For this exercise I want to concentrate on the exhaust. I'll check for the p/n (not sure where to look, but will find it). Will update with that info in the a.m.

 

if you like to tinker, look the the supertrapp supermeg pipes.

they are tunable to emphasize torque or HP. and if the motor is built, can be re-tuned to match.

the stock H-D headers wil support 100 HP+ motors, no problem. and they are already paid for so there is a plus.

a 2 into 1 header will give the best torque numbers if you want to start spending



drilled pipes are usually the 1st try for owners new to harleys who think that "loud is faster" and it's not.

smart is faster.

Mike

 

ahhh, thus my questions.
I have not played around with v twin performance building. I believe I will be picking up a book (recommendations?) a'la the old speed secret books of the 60's-70's I poured over that helped me first learn about modding v-8's as a kid.
I know for best torque one needs back pressure, yet for some reason when I was researching this project I kept reading about drilling the mufflers. I'm not a fan of loud rapping exhausts and realize that power is made ultimate when induction is balanced with scavaging. I cannot wait to learn more about the v-twin and start playing with it.
edit: --> just looked up the super trapps, heck we ran those on roundy rounds back in the 70's when they were new, I was surprised to see they are basically the same!

 

How to build a Harley-Davidson Torque Moster, by Bill Rook and Unauthorized Technical Guide Vol. II , by Donny Petersen. Don't waste your money on the 101 Twin Cam Projects.

 

+1 regarding cams. Exhaust changes can help somewhat, and a free flowing air cleaner does help as well. When I had my first HD an 07 fatboy, the cam change really made an improvement. I then went on to a 103 build and Baisley Heads.

Enjoy your ride.

 

I think I'm done looking for numbers on the mufflers. Unless they are well hid I can't see how I could have overlooked them.
So, I know they are embossed with the words screaming eagle, consistent diameter and equipped with a chromed billet slash cut tip fitted with 3 screws each the end about equal eith the rear fender tip. Likely nothing special.
Thx for the book titles I think I'll check amazon to see if they are in print, or secondary mkt.

 

usually the # is on top near the mounts, with the epa info.

the supertrapps still work great and since you understand them already, you know what I'm talking about.

( and supertrapp now makes 2 models for screaming eagle "nightstick" and "fatshots", which can be disc tuned just like the supermegs and often found cheap !


exhaust tuning is pretty important due to the "uneven" fire and gas pulses of the 45º twin.
the cam overlap MUCH affects the intake charge aside from scavenging, poor set up can have pulses reverse all the way out the intake ( which then leads to threads about "my knee is covered in oil and gas")

for baseline disc numbers, I run abut 12 discs rt and 7 discs left on my 80" bagger ( stock header)
my fxrp 80" runs a 2/1 with 24 discs ( about 28 to 30 discs is as much as the core will flow anyway)
my 96" bagger I run 15 discs rt and 9 discs left- stock header ( no cat).

if going on interstate trip I add 2 or 3 discs a side to enhance HP over torque as I'll be running at 3500 rpm all day.

Important to tune for the anticipated rpm range- most of us spend 75% of our in town riding below 3200 rpm.


the books referenced above are good.

head design has changed since 04 and Donny Peterson has written much since before the introduction of the twin cam that the heads were the least effective part of the motor ( and questioned whether HD did that just to drive a market for screaming eagle heads)

donny peterson writes ( or wrote) "techline" in american iron and runs Heavy Duty cycles in Toronto who have been there since the 70's ( and long ago won the rights to their name and logo...)

I'm doing some home renos and ran across a stack of old american irons, so am rereading before tossing--- man there were some UGLY paint jobs 10 years ago !

mike