Can anyone give me a rough estimate of their mileage on a stock (cai, cat-back) engine?

I am getting just about 200 miles per tank with my new opti.

With the old one I was getting around 160-170, but I thought it would increase more.

If there's anything special to check on an LT1 for mileage, please tell me, I've checked all the basic stuff I can think of (tire pressure, etc).

 

Basic maintanance is the key.
-Fuel Filter
-Spark Plugs
-Plug Wires
-Air Filter Cleaned
-Fuel system cleaned...injectors, ect.

 

My mileage is terrible even after my new opti and ignition parts, tune, headers, etc. Although I think its mainly because my right foot recently joined OPEC

-Dustin-

 

driving strickly around town (slow...stop/go traffic), I get about 210-220 on before I fill it up (just below a quarter of a tank registered). When I take the car on a trip (interstate) I get a little better than 300 before I fill it up. Divided out...I get roughly 16 when strickly in town...but about 23 when strickly on the insterstate.

In town driving is not the best situation for gas mileage.

My car is a 94' with stock engine and tranny. It does have the factory 3.23 gears, and also has an aftermarket muffler (just muffer), Borla y-pipe, Random tech CAT, and SLP CAI. I still have the factory manifolds and OPTI. Sensors and such have been replaced over time, but mechanically it's stock. Also, it's got 98,700 miles on it.

hope that helped a little.