New truck yall

[m3gumby]

Hey guys im the proud new owner of a 99 Sierra Z-71. My first order of business is getting the gas mileage up because the gas mileage on these things pretty much blows. Exhaust is a must. If i want to offroad would it be best for me to have side pipes? What else can i do for more gas mileage? Also my gas gauge is starting to go i can tell, are there any direct replacements that aren't 700 like the dealer told me? I know thats pretty much a crap price. Also it seems like it shifts a little hard, are there common problems with these?

[Trucks!]

well i recently bought a 99 gmc sierra z-71 also, it shifted really hard when i first got it, but i got the transmission flushed, and it shifts really nicely now, firm shifts and i ahvent had any trany problems yet. It never uses/ leaks oil either. My gas milage is between 18 and 22 on the highway and between 11 and 15 in the city, depending on how cold it is, lately in the 10's. I have a magnaflow dual system, with just a high flow cat, and i like the sound and im pretty sure it increases my mpg. i am looking towards a new intake soon, to help boost mine.