Vagabond
So i got a bit bored recently and decided to pull out the baffles on my Indian stage 1 pipes and knocked out the plugs.
Noticed it now pulls a little better. The idle tone has got a little louder but not much which is good but it's when i open the throttle that the sounds gets alot nicer. Has much more of a roar now when the throttle is opened up.
So my next thought was to potentially remove the cats to open up the exhaust a little more.
I know some people might say just get some other slip ons or full exhaust setup but i like the style of the Indian pipes compared to most others out there.
Any thoughts out there on potential issues with removing the cats?
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V-Twin
Vagabond wrote:
Any thoughts out there on potential issues with removing the cats?
Aside from EPA issues, it may require a special tune.  If you already have PCVX, no problem.  It may also loose a bit of low down torque.  I know when I went from Stage 1 to Rush Warhorse, I lose a touch of torque below 2,500rpm but the engine revved out quicker up higher.  I assume, it will be similar but more noticeable?  All guesses as I have kept my cats.  Also, my bike is TS111, not Scout so things might be very different.
Let's be kind to one another.
Melbourne, Victoria
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Vagabond
EPA pffft  [tongue] did realise that could be a potential issues but don't most aftermarket slipons have no cats? Is the potential loss of torque down low sure to reduced backpressure? And would the pcvx negate this problem?
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V-Twin
Vagabond wrote:
Is the potential loss of torque down low sure to reduced backpressure? And would the pcvx negate this problem?
Possibly due to loss of back pressure but I don't know enough about the mechanics to comment further.

I don't believe PVCX can restore what would be lost by free flowing exhaust.  Tune can only do what it can within the confines the hardware.

Re: Cat in aftermarket exhaust - Again, I am unfamiliar with Scout exhaust system but on Thunder Stroke, the cat is further up the pipes, so slip-on pipes don't have cats in them.
Let's be kind to one another.
Melbourne, Victoria
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Flatchat
Hi Guys.  Yes, removing the cats dramatically increases flow through the exhaust which in turn has the effect of leaning out the fuel mixture (in combination with a high flow air filter of course).  Most slip on's don't have cats so this is a well trodden path.  I can say from experience, the lack of cats is only an issue when you get pulled up for an epa check (gunna happen if your exhaust is loud).  Keep your old pipes and swap over if this happens.  

A re-map of fuel curve will compensate by throwing extra fuel in down low (and across the rev range depending on where it is needed).  I can say with my set up that without the fuel map modification, you will lose a bit of low down power but mid and top end is dramatically increased.

Cats ar ether devils tool so getting rid of them is always my preference - for off road use only etc etc etc Ha ha.

If its not too late, the other thing to consider is that removing or drilling out the cats will change the exhaust note.  You may not like what you get, only trying will tell.

Oh, and you save a fair bit of weight....

Finally, without any baffles and the cats removed, you may get a note blue flame at night and a note pop of decel :-).

Love it, have fun.
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Vagabond
Thanks Flatchat.
Found a video of a Scout with plug (though they call it a baffle...maybe i'm thinking of different things...to me the baffle is the whole assembly inside the exhaust...correct me if i'm wrong) and cat removed...actually doesn't sound a whole lot louder at idle which the neighbours might like as i start bike at 0530-0600 in the morning [tongue]

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srd0060
Vagabond wrote:
So i got a bit bored recently and decided to pull out the baffles on my Indian stage 1 pipes and knocked out the plugs.
Noticed it now pulls a little better. The idle tone has got a little louder but not much which is good but it's when i open the throttle that the sounds gets alot nicer. Has much more of a roar now when the throttle is opened up.
So my next thought was to potentially remove the cats to open up the exhaust a little more.
I know some people might say just get some other slip ons or full exhaust setup but i like the style of the Indian pipes compared to most others out there.
Any thoughts out there on potential issues with removing the cats?




if you don’t mind me asking how did you remove the Plugs in the exhaust, I have removed the cats I just drilled through them and knocked the rest out with a screw driver and hammer.
2018 Scout, Thunder black, Beach bars, DART screen Bobber Rims, Stage 1.
IMRG  AU 101571
Ulysses  67236

Canberra, ACT
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Vagabond
srd0060 wrote:


if you don’t mind me asking how did you remove the Plugs in the exhaust, I have removed the cats I just drilled through them and knocked the rest out with a screw driver and hammer.


Knocked them out with a long piece of 25mm bar and a hammer.
They are only held in by 3 tack welds from memory.
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srd0060
Do they get overly loud, the reason I ask I owned a HD 1690 streetbob with straight through pipes and OMFG.
2018 Scout, Thunder black, Beach bars, DART screen Bobber Rims, Stage 1.
IMRG  AU 101571
Ulysses  67236

Canberra, ACT
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Vagabond
srd0060 wrote:
Do they get overly loud, the reason I ask I owned a HD 1690 streetbob with straight through pipes and OMFG.

Not particularly louder as to you'll still have the baffles in.
Is a little louder at idle and alot more when you give it some 😉
Removing the car and plug is more about removing some of the restriction in the exhaust not all of it. Back pressure in an exhaust is a good thing. Keep in mind modifying the exhaust like this will cause engine to run leaner some what (moreso if you do air intake as well)....if you have the $ invest in a Dynojet PVCX... Best money you will spend 👍
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srd0060
Vagabond wrote:

Not particularly louder as to you'll still have the baffles in.
Is a little louder at idle and alot more when you give it some 😉
Removing the car and plug is more about removing some of the restriction in the exhaust not all of it. Back pressure in an exhaust is a good thing. Keep in mind modifying the exhaust like this will cause engine to run leaner some what (moreso if you do air intake as well)....if you have the $ invest in a Dynojet PVCX... Best money you will spend 👍


i will drive a screw driver up it rear tomorrow to knock the tin plate out, as I said the cats are done.
2018 Scout, Thunder black, Beach bars, DART screen Bobber Rims, Stage 1.
IMRG  AU 101571
Ulysses  67236

Canberra, ACT
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