My local muffler shop does a custom cat-back exhaust with your choice of muffler for $275. My question is what diameter piping should I look into getting for the best performance gain... They will go up to 3" on their piping, is that too big?

 

Real expensive if you want stainless and stainless weld.

 

Assume money is no object.

 

I think it would be fine if its installed after the cat. Are you going to use the factory muffler?

 

No I need to pick out a muffler too...

I read online that you should take the estimated hp at the crank with open exhaust, multiply it by 2.2, and that should be how much flow you should be getting from your muffler.

In my case, I estimated my hp with open exhaust to be 210, which would mean I need 462 CFM of flow... But I'm still confused about how everything is going to come together...

I think the problem is that I want PERFECT. Or at least to know perfect when I saw it... I have no idea at this point how to mathematically figure out the perfect length and diameter of the exhaust system to produce optimum power...

 

I didn't know what the forlmula was for determining the exhaust diam.

On my "01 Impala I had the resonator removed and a Y pipe installed behind the gas tank. From there two stainless mufflers welded on. so from the cat on back, the diameter went from 2.25" to 2.75." Ran fine but the droning was excruciationg when ya had a hangover.

After a few years from driving and sitting in the snow, (I did not have a garage yet, nor did I shovel,) the aluminized pipes rusted.
I ended up getting stainless pipe put on, magnaflow resonator and, two new mufflers. Costing almost $1,000.00. (2.50" diam by the way.)

See what the diameter is on the cat back kits that are out there. Might be be a good reference.

 

Well I am currently wondering where the heck I can even find a muffler for my blazer... I mean, the shop I'm going to do it at said they had some... But I don't want some low flowing flowmaster... and if I buy online and simply have them install it, I'll prolly save a pretty good amount of money... Anyone know where I can find a fitting muffler application for my blazer?

 

Anyone know how much the stock muffler flows (in CFM)?

 

Depends what brand you prefer. CLick here for Pacesetter.
CLick here for Gibson exhaust.

 

First off you cannot "gain hp" from an exhaust systtem. The hp comes from the engine, the exhaust system restricts the amount of hp the engine can create.

The simple answer to your question. 2 1/2" pipe.

The muffler with the best flow rate is a glasspack.

Most aftermarket performance mufflers have baffles that redirect the air flow to aquire a tone. They provide less restriction compared to a stock muffler, and thus increase your engines hp slightly, less then 5hp. A stock muffler runs the air through the muffler 3 times before it exits the muffler.

The best investment, if you really want to increase hp, is to get rid of the stock exhaust manifolds in favor of some headers. The exhaust manifold/headers, collector pipes, y-pipes is where you will have the most effect on your engiens performance. By time the exhaust gets back to your muffler, there isn't much difference you can make in freeing up engine hp.

The cat back system is designed for sound. Is that tone really worth $300.