Hey guys so im buying a 95 Z28 tommorow with 133000 km which is bout 70-80k miles. The government EPA mileage for mixed city/hwy driving on this thing stock is 18 mpg. I was wondering how much worse it is with the current mods it has:

305cc cam
asm headers
borla exhaust
1.6 roller rockers
k@N intake
new springs + struts + breaks
new electric water pump
new gaskets

The catalytic converter has just been put back on.

How much less you guys think the mileage is with everything listed and how much it is with and without the catalytic converter.

Thx guys any feedback appreciated

 

im going to take a guess and say somewhere around a little over half of what the EPA had for it, if you resist the torque fever...

but in areally optimistic perfect world id say 14 - 15 sounds resonable

 

The only thing that can really have an effect on the milage is the cam that it has (are you sure it isn't a "CC 305"?), and milage really depends on how you drive it...

 

I have a 94 z28, auto, stock engine, K&N, magnaflow catback, and average 18 city/24 hwy. Just made a 333 mile trip on the highway, stepped on it less than 6 times (personal record) on a single tank of gas. 13.7 gallons refill at the pump = 24.3 mpg. Can't complain, ran it 70-75mph most and alot of uphill grades in Northern California.

Doesn't really answer your question about the difference in having a cam, but I agree with the previous poster. Pretty much apples and oranges if you enjoy the torque lust.

btw, 184,000k on the LT1 and it purrs like a tiger.