This is for rcign:
You have probably play with more than a few of the piston ported engines.

Anyway- using piston ported engines,
Have you ever tried tuned exhaust systems - not peak power setups - -but pipes which boost -some-even a tiny bit- and have an absolutely smooth bottom idle to full torque reading?
Did you find they responded well?
Easy to do ?
I find many modelers very reluctant to even try a quiet, power adding system on these piston ported types - such as the Sach- the Zenoah- all of the new similar sporty offings -FPE- Fox -Fuji etc.
I get asked about this -a lot! but inasmuch as I don't have any piston ported engines - I can't really offer any help.