running a test pipe, better mpg?
 

will running no cat converter and a test pipe instead aide in increasing overall mpg?

Yes, unless you are flooring it everywhere you go, then you may decrease a hair.

No it will not increase your MPG. I have a Megan test pipe and you will notice a huge lost in my MPG. And I am considered as a "Granny Diver" BTW. I might be wrong but this is what I have encountered for all most two years now.

i got a complete megan exhaust setup my MPG only drops when I floor it alot but otherwise its pretty much the same 30+ MPG City

looks like i should be putting my cat back on.

same question applys to a catback exhaust system...will an aftermarket (specifically the apexi world sport) increase or decrease my mpg?

imo loss in backpressure loses mpg and don't you lose hella backpressure when you take out the cat? and especially when you put bigger piping?

Bigger piping will in theory decrease you MPG because you have shifted you power band up, meaning it now requires the engine to produce more less effiecent power (read more fuel for the same power at lowwer RPMS). In practice, I don't think it will make a difference untill you start flooring it.