Can anyone give an idea about what I could gain in mpg with a corsa catback and the upd?

5.3L w/3.73
Only mod at the moment is ASP pulleys.

 

Well, I ordered the UPD and will be looking into the Corsa rear exit exhuast and possibly the predator tuner sometime later in the month. Also considering going back to electric fans, but using the Flex-a-lites instead of the OEM F-body fans like I did in the past.

Here I go again spending my money and credit on my truck. I decided to keep the thing for as long as possible and just get it repainted in a year or so. I have had a car payment from the time I got my DL and it would be nice to not have a car payment in a year or so. But of course I'll just go out and buy another car shortly after.

 

I didn't gain any MPG with these 2 mods...

 

Not enough to offset the price of a Corsa. Well, maybe after 15-20 years.