this happened to a friend of mine and im just interested to know if this has every happen to anyone or what may have caused it
he drives a jdm 2000 euro R .. he dyno tune it a few months ago and got 202whp ..
mods include
wisico pistons ans rods
set of dc sport headers
2.5 exhaust piping to a reactive exhaust pan
aem cold air intake
tuned ecu (obd1 i believe)

since then he made some more mods but these mods resulted in a drop of 70whp (153whp)
went to 3inch piping
upgraded TB to 68mm
port matched intake mani
cam gears (not sure if it was exhaust or intake that he adjusted - however the car runs much richer since, gonna guess exhaust)
and retuned on a dyno jet with same original tuner

as stated he droped 70whp , he put back on the 2.5 piping and made 170whp i beleive he also set the cams back to stock setting when he made the 170whp ..

anybody have a clue what the hell would have caused such a massive drop ..

i still think he should have went cams instead of pistons tho

 

Maybe he over ported/polished

 

hmm coming to find out that the pistons where just forged pistons .. no increase in compression ..
kind of confused as to why he even bothered to go to 3inch piping on that .. thats not enuff back pressure for the stock compression rate ..

 

that or valve overlap could have been to excessive and not building enough compression on the compression stroke

 

could this have been caused by the cam gears ?? wrong cam being adjusted or adjusted too much ?