How to know which pipe to use.

[Gabriel Gonzalez]

  I got a 7.5cc Macs quiet pipe for my 140FZ, but I'm not sure if it's the
  right thing to use.

  How can it be determined what would be a good pipe to use with a 4c
engine?

  7.5cc seem awfully small, but in an earlier post I saw someone using a
 3.5cc
  pipe!!!! Was this a typo?

  I don't want to ruin my engine or my plane, and thought to ask before
 trying
  it.

  Thank you,

  Gabriel González


=====================================
# To be removed from this list, send a message to 
# discussion-request at nsrca.org
# and put leave discussion on the first line of the body.
#