Just added a new borla S type axle back exhaust on my car. Heard I might see some gains in fuel economy etc.. I don't have the means to dyno my car or do any crazy tests to monitor potential gains. Anyone have a ballpark idea of what kinda increase HP/torque or fuel economy gains I may see, if any?

 

Axle back is not going to give any real HP gains or fuel economy, just for sound.

You will lose a few pounds of weight though.

 

Borla's website says there are hp/tq/mpg gains, but I have not seen any hard data.

The general rule is: don't expect performance gains from cat backs.

 

If you see any gains from axle backs it will be minimal at best (1-2 hp) and I would think it would be hard to tell any difference besides on a dyno maybe. They just offer sound improvement. I can see if you did a cat-back. If you take off the piping from the x-pipe to the muffler you will see all the unnecessary bends and how restrictive (on our V6) it is as far as air flow so upgrading to an aftermarket cat-back will help it flow better.

 

So full catback vs jus the axle, is there a considerable difference as far as any gains? The difference in price was about $500, I know I can always replace the other pipes if I want to. But are there really any glaring differences between the 2 that make doing the full upgrade better? I'm very impressed with the exhaust system on the new v6 and read that the most restrictive piece of the whole thing were the mufflers as opposed to the pipes.

 

Depends on what you consider "considerable".

Probably 7-8 HP for a catback on a V6.