which first?

[dorkins]

drive about 70/30 highway and city

would i be better off getting 3.73's and new differential? how much would this cost to install on average?

or, would i be better off putting a 3" catback in it

i will be puttng a whisper lid in sometime, but have a home made smooth bellow and shaved air lid for now

i will also be gettin new headers after the catback

will i see more gains with the catback, or the 3.73's?

[i_love_my_maro]

I would do the Exhaust first then the gears. your gas milage will get better with the exhaust then worse with the gears. although that is just my opinion.

[shenanigans]

the gears will hurt your gas mileage, catback will likely help it.

[ellik]

if you can do headers and exhaust at the same time, that is the way to go.... just makes things a little easier.

[V8 Killer]

Exhaust first.

[dorkins]

that makes my decision easy...

and, after reading more... it seems that calibrating the speedo for 373's is harder than for 342's
is that true?

also, what should i be getting off a tank of 87?
on a stock 98 3.8l ?
i am getting just under 200 miles/tank which seems rediculously low...

i got about 230 on 89

[john00v6a4]

do the exhaust first definitly...... as for your gas milage that seems really low. you should get way more than 200 miles on a full tank.

[i_love_my_maro]

I get aprox. 350 per tank but i always fill up before 300 i just like having that buffer.

[dorkins]

really...?
wow...
what could be causing this low mileage?
only has 57k miles on it

i have gone thru 4 tanks, and have gotten about the same every time...
wtf?

[john00v6a4]

it can be multiple things. your fuel filter might be bad. scan the car and see if you are throwing any codes or anything like that.

[dorkins]

how do i do the diagnostic scan?

[oil pan 4]

You can't unless you have a scaner.
Take it to a GM shop.
It could cost up to $50 but shouldn't.