I asked a similar question on the Rushmore model forum.
Does the increased compression of the water cooled 103 engine change anything as to whether a tune is needed if slip on mufflers are put on the bike.
Thanks in advance.

 

my opinion is that the catalytic converter in the exhaust header is the bottleneck to flow in the exhaust tract, not the mufflers- especially if the stock air cleaner is retained (it is somewhat restrictive too).

so- in your shoes i would go with my choice of slip ons.

with caveats:

1.) I know what pinging is and can recognise it- persisent pinging can damage your motor.
1b.) in which case I would probably use nightrider.com vieds/xieds for tuning compensation ( many riders prefer other devices)- if required.

2.) I would get a header with no cat and a high flow aircleaner...these added to the above will result in about 10 horsepower gained- for minimal additional cost. maybe $280


that's what i'd do.

Mike

 

Nope. Put 'em on and ride.

 

from I have gathered, the 14 and up Rushmores have a better flow through the air cleaner --

and really, the cat is the restrictive part of the system -- should not have to do anything more --

 

The ecm will compensate for a slight increase in flow. It will still run an A/F of 14.7-14.9, in other words it won't run all that much better. Go for a tuner and dyno tune and really enjoy the ride.........