Here is what I have:

84 Z28 305 5.0 HO L69 engine
4bbl
4 speed auto
completely stock
84,000mi


I would like to get a new exhaust and filter for it. You will have to excuse me, because I dont know too much about car mods, but I have an idea behind everything from modding out dirt bikes and motorcycles. I was thinking on something like K&N and a flowmaster but I dont know if I will have to re-jet the carb because on motorcycles, it was necessary if you put on aftermarket parts. I'm not looking for extreme hp increases or anything, but more would be nice. I would like it to sound meaner than what it is but dont want it to be so loud that i cant hear the radio. Should I get all new exhaust including new headers or just a catback system? And if not Flowmaster, which one? Also, can anyone recommend any kind of tail pipes that will come out past the rear bumper? You cant even see the stock exhaust. Is this because the plastic will melt? Thanks for any help.

 

Definitely K&N, and headers with a CATback, as for sound you can fine sound files on this board, but each manufacturer should have them on their websites. My tail pipes stick out, but bottom out on some drivesways & inclines. It shouldn't get hot enough to melt plastic.

 

I have used Hooker headers many times. Most recently a set of shorties on my wife's 92 Camaro RS. Always liked the quality and fit. Some of the best on the market. Defintiely get them ceramic coated for long, pretty life. SLP stuff is nicer than that but you'll pay a mint for it.

Shorties with 1-5/8" primaries and a complete 3" exhaust all the way back through the muffler will do just fine and be a nice improvement over stock without breaking the bank.

K&N in the stock dual-snorkel air cleaner will help some. For the summer time you might want to de-activate the hot-air system (that draws hot air off the exhaust manifolds) to keep intake temps lower. Re-activate it for the wintertime, however.

I also agree that just swapping out the stock intake for a standard Edlbrock Performer (not even the RPM version) is worth a nice 10-15HP bump, even on a stock motor with basically no downside except the cost and time to install it. It's even emissions legal and weighs less than the stock manifold (if your motor came with a cast iron intake). All your stuff will bolt right up, even the emissions and engine sensors.

Bump up the timing from it's stock 6* setting to 10* for better performance with premium gas.

 

but will i have to rejet the carb?

 

You're not going to get anymore hp by using a K&N filter.

 

I just put a K&N filter on my crap bag 4.3L van and gained a consistant 2 MPG. Must be good for something.

 

I agree. If you do have the factory dual snorkel aircleaner as you claim, a switch to a K&N would be beneficial with the addition of a larger truck aircleaner lid. Some truck lids allowed the use of a 3" filter element, and will provide a performance increase over your standard lid. It worked for me. It doesn't provide more airflow, but rather provides more clearance above the carb creating less turbulence.

IMO tailpipes that stick out past the bumper look bad. You can get tips that are visible unlike the stock turndowns, but terminate at or just before the bumper. The plastic will not melt as long as the tips don't touch.

You don't rejet a QJet like a Holley, you swap metering rods. Same thing, but a different approach. Again, if you truly have the L69, your carb has a performance tune from the factory that should be adequate for the bolt-ons.