20hp!!!!
haha
nope.
id say it certainly wont me making more HP, but i doubt you coudl measure the horsepower loss. think about the restrictions the mufflers cause.
what engine you talking about? i have 2.25" all the way through on my 4age (with cat resonator and straight throught muffler).
since you say its timed at 12BTDC i assume you mean a 4kc or 4ac. if so...do they even make 20hp
i swear my old 4kc didnt make 20hp.