Kits? Arfs?
Most new kits and Arfs are built to appeal to the rapidly increasing "model flier " who can not or chooses not to do any work other than some assembly-
This is a part of evolution - which was bound to happen.
I have also stuck together quite a few of these.
Some good -some simply POS.
(That's pieces of crap )
If you do however, like to do custom stuff - most kits will readily adapt.
I have put tuned pipe inside H9 TCraft -with a 40 .
great setup -but not recommended by Horizon!
Way too much power - their words -not mine.
As a suggestion - just a suggestion -the new ZDZ40 Sportsman with the attached Bisson muffler is a compact setup -(rear carb -close fitting side muffler) Which should fill some tight cowl setups.--No mods to airframes.
I like the cans and pipes for the quiet power .