slicky rick

Installed hacked mufflers and took her for a drive..sounded awesome but felt it lost some torque... Imagination? Or has anybody else felt the same?

cjjones

Can't help you with the torque question. Did you replace the center muffler as well?

utkinpol

car is so loud now you do not step on gas as much as before.

Mufflers do not add nor reduce back pressure much. Still gundo hack interferes with a flow direction a bit so you may feel less torque in hi rev area, but it should be be felt in low rev street rpm range.

Disconnect battery for 5min and drive it hard after that to redo ecu mapping adjustments. It may help.

slicky rick

hi paul, is the disconnecting the battery for allowing evertyhting to adjust again a good idea to do every so often or everytime something is changed like muffler, sparkplugs, oilchange, etc. etc. i think i will post that here in our forums to get our brothers inputs.
nevertheless my analysis of the situation is the gundo interferes with flow of gases out. it might provide more friction in the system. this increase in back pressure should help torque in the low rpms but might affect the power we feel in the higher rpms. maybe i am mistakenly calling this feeling for lack of torque in the high end.

utkinpol

Technically ecu should adjust over time but I noticed when you make exhaust less restrictive timing shifts odd in first and it feels like drop in power. Try to reset ecu by power disconnect, if it does not help then it is something else. Also make sure you have no leaks in exhaust connections.

slicky rick

gundo creates less back pressure? i thought that it was the opposite as we are creating new bends and adding turbulence in the connection. though it might seem to give less back pressure, since we are having more noise, i would think otherwise… nevertheless you are absolutely correct with the odd shifting thingy. at first drive the transmission seemed to be looking and not doing it right. slipping all over the place not know when to go into gear. however after a sprited long drive everything was back to normal with great shifts.

PhilD

I would definitely think less back pressure as you allowing a portion of the gases to bypass the muffler. I haven't noticed any power reduction with the hack, if there is any it isn't enough to notice. Unlike bypass pipes which definitely rob you of some low end grunt.

I've never bothered disconnecting the battery after changing anything, just a few hard runs and the ECU seems to adjust fine to any changes.

mdrums

I doubt the Gundo hack creates much more air flow...not enough to effect HP or TQ. Where you notice what people call a lose of TQ down low is when you go to short tube headers and 200 cel cats. long tube header work better....but the TQ just moves up in the rpm range.

For me I don't care about TQ at 2000-3000rpm because I am never at that rpm at the track coming out of a corner where I really need max TQ...I want my TQ up in the 4500-5500 rpm range and HPf rom there up to redline.

slicky rick

for track i would agree that less back pressure would be good a this increases hp up top and moves the torque curve higer in the rpm range. totally agree mike. i just wondered why pdk acted as if adjusting after the hack install. i would think there was something the computer noticed. everything is working fine now thank you but just having a good discussion.

USMC_DS1

FWIW, I felt a slight lost in lower end torque along with better mid-range after installing FVD's long piped headers and 200 cell cats. But after an ECU remap from FVD it all came back... so I think you should try what utkinpol suggested. If that doesn't work then an aftermarket ECU remap may be the next step.

slicky rick

usmc that is a slippery slope...when we start doing that we never end. hahahah. all is fine right now after ecu adapted...i havent tried the high end yet as i havnt gotten the chance but will tyr again this weekend

slicky rick

i am just curious because i never thought the hack introduced enough difference in exhaust flow to need an adaptation by the ecu.