I need to put the quiet on the LT1 Roadmaster Estate Challenge car since I will also daily it. The car came with factory 2" (or less?) dual exhaust, the most restrictive manifolds ever, 2 cats, 2 mufflers, 2 resonators, a few lead ballasts for NVH damping, and a partridge in a pear tree. I've taken out everything and the weight savings are adding up. The engine has a sick nasty cam, homebrew porting job, cold air, and headers.
I was thinking dual 2.5" straight back from the headers, some kind of muffler or glasspack, and dumping before the rear axle or out to the sides. What's the cheapest way to do this that will flow well, weigh not a lot, sound badass, and still be road trip worthy? Will a muffler shop sell me cheap tubing and flanges? Should I test out using the stock resonators as mufflers? Berk it and turn up the radio?
Earmuff Headphones Are the proper way to do it.
Put the stock exhaust back on after the Challenge.
I ran 2 1/2 od from headers straight back too a pair of thrush welded mufflers dumped in front of the axle on my marquis and liked it almost as much as the flowmasters on my capri.
Cheap, quiet down low and didnt weigh a bunch.
If you use a chambered style muffler (Thrush Welded or Flowmaster) with turndowns you'll have drumming under the car.
If your budget allows Dynomax Ultro Flow or Super Turbo - work good. Also, Thrush glasspacks. Longer is quieter. Summit Racing has a cheap glasspack - louvered style vs Thrush core style.
Stock exhaust setup and non-electric cutouts?
Back in the day I had Summit Racing chambered mufflers on my Duratec Taurus. They sounded good, but they rusted out in a few years, but for the price and for the challenge, they'll probably work great. They're definitely the poor man's Flowmaster.
Summit Racing Mufflers
(this is an example, they sell them in all kinds of diameters and inlet/outlet configurations).
Build the exhaust around your DD needs and also factor in the ability to unbolt the majority of the exhaust system.
At The Challenge, take off all you can which therfore removes the corresponding exhaust dollars from your budget.
Add in driver safety earmuffs which as safety, do not have to be budgeted.
Do not do the pre-axle dump on a wagon. I did it on mine for all of about a week; it wasn't a loud exhaust but the resonance from having a big open space in the car was horrible. Axle dumps on a car are fine because the cabin is smaller and the trunk bulkhead helps to isolate the noise.
My daily setup on a ~375crank hp engine: long tube scratch and dent headers for $50 on ebay, dual high-flow cats, decent Y-pipe to a single exhaust because daily driver. All this through the biggest straight through muffler that Summit sells, over the axle, and out the back.
For the challenge, put together your DD exhaust but put a V band or something in front of the muffler. Build a second rear section for axle dump or something to save weight and restriction, but then you can easily swap back to the street setup.
Do not put your glasspacks bloted to the headers and then run your pipes out to alex and out the side. Very annoying as hell. My delta had this. It did not last long before I got annoyed and changed it.
Dual dynamax (or other knockoff magnaflows with a straight through design) and spit the exhaust out the SIDE in front of the rear tires. Ive got a wagon which has had both dumped under the car and spit out the side and out the side is quite bearable. Then you dont have to worry about the big humps to go over the axle or deal with whole cabin droning.
I've never had or ridden in a car with an under car dump that I liked. Even a few inches inside vs. outside the pinch welds on a side exit setup is a big, no longer need earplugs grade difference.
Get the longest glass packs you can. Walker, IIRC, has them unpainted through Advance Auto really cheap. Side exit ahead of the rear wheels, past the pinch weld.
Those manifolds aren't actually too bad.. they are the ones that circle track guys look for these days..
As far as the rest of the exhaust goes: 2.25" lead pipes, X pipe, more 2.25" pipes, either Flowmaster or Dynomav Super Turbo mufflers in front of the axle, 2.25" tailpipes out under the rear bumper..
