In the next week or so my tp go's in to have the VP commie cat grafted in and the cat forward changed to 2.1/4" now do i change the flex pipe to 2.1/4 or leave the stock one in?

My stock hollow cat is going as my system flows a little too well unless your floggin it the oxy sensor isnt getting hot enough to give an accurate reading im hoping the commie cat (cheap highflow as its 2.1/4 in/out) will slow things up enough to let the o2 do its job & maybe use less fuel & legal emmissions, what do you guys think?

pete

Tommorow is the day for this IF the exhaust centre will stop being dicks 1st quote was $60 over the phone now they want to see it 1st as im supplying the flex pipe and cat both new mind you, if all go's well ill have full 2.1/4 system & legal :D

Pete

Got my car back at 4pm all i can say is sweet!, The slugishness from idle to 2800 rpm is now gorn it pulls verry hard from idle so id say my o2 sensor is doing its job now, will be interesting to see if my fule usage drops now (if i can keep the boot out of it). cat back system is nice but full 2.1/4 is the wtg

sounds good ey, mine will stay cat back for now, yours must go a fair bit better than stock now with full exhaust and whatnot :D

Did you change the manifold?

just a small update with my fuel usage since the full system & cat is in, weekly runing cost reduced from 32-35 ltrs a week to 25 ltrs doing around 300k's, the missus even said the car doesnt stink like hell like it used too what did you do :D