New Exaust need some help please
 

Im looking into putting in a new exhaust, I want to go with 3" pipe from the manifold, and drop the cat, and go with a performance muffler.

Questions:

1. What muffler would you recommend? i was looking for a little more sound but nothing ridiculous. I was sort of interested in the Flowmaster 40 series. Anyone have any experience with these?

2. When i was giving my exhaust a look over there was a small unit upstream of the cat, what is this? it is sort of a pre cat?

Three things:
1. If you drive on public roads in the US, be aware that not having a catalytic converter is a Federal violation. 'Nuff said.
2. There are lots of threads here concerning choice of mufflers. Have a look around and also check YouTube videos, there a bunch of them about Blazer mufflers.
3. Yes that small unit ahead of the cat would be a pre-cat.

Really need to know more about what it is you are driving...

I would recommend just getting a high flow cat to replace yours. As far as the pre-cat i dont have much experience with those i dont know if you can just get rid of it and go with a highflow cat (anyone now about this). And as far as the muffler thing goes like its been said theres tons of sound clips and videos around with blazer mufflers just need to keep in mind that some guys run no cat or high flow cats that will change the sound a good bit.

I am driving a 2000 2Dr 4x4 with the 4.3L v6. I was looking at some high flow cats, i think i will leave a flanged area in the pipe so i can put my cat in if it is getting checked, they don't check our cars here in Florida...yet, but i don't plan on drawing enough attention to get caught.

If that unit is a pre cat its as good as gone. I will also check out the threads for mufflers, thanks for the tips.

I would try doing a cat back set up first. You can always do the pre-cat exhaust later.

Also I have been getting around 15 mpg which seems a little low, my buddy with the 01 4 door 2wd gets 20-21 mpg. I don't even push it past 2k rpm, but realisticly could i see a 1-2 maybe even 3 mpg boost? The engine runs great, i think maybe my cat is plugging up.

usuaully a 4x4 wont get as good mpg's when compared to a 4x2, you may see an increase in mpg's after ur exhaust but i doubt youll be close to ur buddys blazer.

the efi system takes a week or so to adjust to the new exhaust with less restrictions. give it time and see wat happens.

I have a 98 blazer I just finished my custom exhaust on if you want some help. I replaced everything from stock cat back.

that little bubble if you have it, is a resonator before the cat. I think..My old jimmy had it and thats what I remember it being. My 98 blazer doesn't have it though.

I ran a magnaflow high flow cat (one of the only catalytic converters I could find that would still pass emissions, guaranteed) which runs about a foot of pipe into flowmaster 44, then dropped almost immediatly after with a 2 inch downturned tip. Sounds good, has a nice purr, a bit louder than my friends stock v8 chevy.

My mileage is at 13, I only drive city really. mine is 4x4 with a brand new crate engine that just crossed 4k miles, body has 145k.

video if you want.
http://www.youtube.com/watch?v=ONgriXW2BEM