M8 Exhaust

[DRod]

saafrican,

let us know how you make out.  I have the 17 SGS w/stage 1 (SE street cannons and heavy breather intake, SE tuner) but was also considering a cat removal.  it doesn't look that difficult.  I don't want to cut and weld like others have done.  it needs to remain clean and stock looking.  if I can't do it then maybe i'll do the American Custom Exhaust header swap for $199.  I believe it's called the powerflex system.  they replace your stock header with another stock set that's been modified.  (they don't just remove the cat)

[tomcat64]

we did our first one a couple of weeks ago,, SE 447 cam, V&H power dual head pipes  with Rinehart 4" slip-ons and TTS tune,, made 94.42HP and 112.39TQ

[Glide17]

I would have thought there would be a bigger difference with a decatted head pipe. I have the cannons stock head pipe ventilator and 447 cams se street tuner and I got 109 tq 92hp. Apparently Harley did a good job opening up that Cat and getting more velocity in that pipe. It works more like a 2-1 than a 2--1-2 looking at how little exhaust exits the left pipe and the angle at which it has to go to exit.
Still like to lose the cat just for heat purpose alone

[tomcat64]

we got 84 and 104 with the stock head pipe,,

[Glide17]

Well that's a good gains  with that pipe then.

[saafrican]

Hi Guys .
This is what I have done .
SE stage 1 air cleaner , amazing improvement
SE  stage 1 ECU tune , to keep the air fuel mixture right .
I used a 42mm hole saw and cut open the standard exhaust tail end cap.
The 42mm hole saw just fits into the opening . Once the end piece is drilled out , the exhaust pipe has no restrictions . None at all . Its possible to look inside and see the catalytic  converter inside the collector box .  Take a SE Cannon , its the same , STRAIGHT THROUGH .

According to Harley the SE stage 1 kit increase the torque to 107 at 3500 rpm (that is 85 MPH )
Doing the above costs about $600 including the ECU installation
I did NOT buy Big  Cannons , little cannons . S&S  Fuelly Pipes  or any other pipes because they are around $500 $600 , and make more noise

Harley SE stage 2 costs $2500 ,and increases torque 1  maybe 2 ft/lbs   but at higher  revs   i.e. 3750rpm    Heck thats  90mph    WHO CRUISERS AT THOSE SPEEDS 
I can't justify $2500 for 2 ft/Lbs torque increase yes the torque curve is flatter   but for $2500  
NO THANKS    to expensive for not much useable torque .

With only the tail section of the exhaust pipe cut out ,Ive gained the benefit of an open exhaust pipe  and saved $550

The other big advantage for me ,  there isn't an obnoxious noise increase , It is a little deeper ,but NOT RAUCOUS , because I haven't removed any sound proofing from the exhaust pipes .

Because Ive done SE modifications Ive kept the Harley warranty , Saved $550  and gained max Torque/dollar

To ride.?
MAN THIS BIKE IS NICE   there is so much pulling power right from idle .
The most noticeable is from 1000 to 2000 RPM .

From 60 mph  when you  crack the throttle open in 6 th gear the bike is VERY strong and the road get narrow real fast .

IF you thought the M8 is nice !!!!   do these fairly cheap mods  and you will really love your Harley 

[Sunny Jim]

So clearly the M8 header is different to it's predecessor.
With the advent of aftermarket exhausts eg. Fulksac and Fuelmoto, will the previous model slip ons fit the new proposed headers from manufacturers like formentioned suppliers. Any clues?

[Jamie Long]

Our M8 Jackpot head pipe uses 2017 specific mufflers with the larger right hand inlet and was designed as such.

[Partsman64]

    Is anyone working on a 2 into 1.

I talked to Vance and Hines.......They said a new Propipe would be available probably late spring, early summer.   

[wumhenry]

Why pay for aftermarket M8 headpipes?  Wouldn't you get essentially the same thing by decatting the stock pipes?   

[Sunny Jim]

I am looking at this M8 header and thinking this thing is really modelled on a 2-1. It's like the left pipe does very little. Any thoughts?

[DRod]

interesting.. I did a muffler swap and only made a slight improvement in performance and sound.  While doing the swap I examined the cat and thought about drilling right through it.  has anyone considered this to allow more air flow?  I don't think you need to completely remove the cat.  doing so will also eliminate whatever back pressure is required. (assuming some back pressure is required) But by allowing more air flow wouldn't it give you better sound and probably better performance that stock? 

I'v got my long drill bit standing by! 

[rigidthumper]

I'd think exhaust flow could be disrupted by the crushing action action of a drill bit.  Maybe try a long core bit of the right diameter to remove the cat?

[DRod]

not looking to remove it completely.  just trying to allow a bit more airflow.  If we do need some back pressure than we may still need this piece in place.  opening it up a bit may help with sound and performance.  I read someone had completely removed the cat only to discover the bike lost pressure and thus power.  Can anyone confirm this?  will removing the cat altogether create a problem?  obviously I'll need to retune, but i'm talking in addition to that..  I want to start off slowly.. 

[rigidthumper]

So far, it hasn't proven to be a restriction. I've seen testing with the stage 3 kits, stock headpipe, slip on mufflers and SEAC make almost 120TQ and 115HP, and be EPA/CARB/DOT legal.

[Sunny Jim]

A dealer , here in Western Australia, has been installing 09 - 16 after market slip ons with a manufactured reduction sleeve on the RH exhaust outlet. Allegedly discontented owners have been having heat and blown head gasket issues on these exact bikes. Another dealer has been replacing head gaskets and exhausts with no further issues!
Any thoughts?

[slimatsea]

So clearly the M8 header is different to it's predecessor.
With the advent of aftermarket exhausts eg. Fulksac and Fuelmoto, will the previous model slip ons fit the new proposed headers from manufacturers like formentioned suppliers. Any clues?

Bassani true dual down unders are out now and they fit the 95-16 slip ons. I'm really tempte to go othat route because I hate the look of the factory fat right muffler but I'd be really pissed if I bought headers and lost performance. I don't have much faith in true duals to make great power.