exhaust

[rvaedge]

I have a flowmaster exhaust with a 3" outlet, and I've decided that I'd rather have a 2.5" outlet. Can an exhaust shop put an adapter or anything on to make the outlet size smaller to fit a 2.5" pipe? Also, I've never had any exhaust work done? Two questions. Go with a smaller local exhaust shop, or a well known, more established shop. I would assume the smaller shop will be cheaper and better, but may take more time. Second question, do exhaust shops do estimates over the phone, or do I need to go to the shop to get a cost estimate? If it's legal I want to dump the secondary cats and put the muffler where they are, put the 2.5" adapter on, and have a 2.5" pipe going to the back. If its not legal to get rid of the secondary cats, then I will just replace the existing muffler with the new one, and run the 2.5 inch pipe back. Do ya'll have any guesses how much that would cost. I got a decent tax refund, so I'm using some of that to put the exhaust on! Thanks

 

[410Fortune]

Why do you want to go from 3" to 2.5" on a V8?
3" is better.

You need to check with VA to find out if 4 cats are required on your 5.0L truck.

The rest of your questions = any exhaust shop should be able to help you with any of this work, just use the phone book and talk to a couple until you find one you like. Then be VERY careful describing to them what you want.
Typically I am under the truck with the guy pointing and shoeing him what I want and why.

 

[rvaedge]

I know you swear by the 3" for a 5.0, but I just want something a little smaller because I do a lot of highway driving and I dont want the drone to drive me wacko. I'll try some of the local exhaust shops and see what they say, and then maybe take the x up to the ones that I like and show them exactly what i want done and go from there.

 

[celly]

Why do you want to go from 3" to 2.5" on a V8?
3" is better.

Why is that? I'm not doubting you, but using the rule of thumb that Flowmaster mentioned on their site (can't find the link, they moved their site around recently), 2.5" is better based on the HP the 302 puts out in an Explorer. Obviously there are no hard and fast rules, but I'd like to know if there are any reasons why I shouldn't have 2.5" pipes on my Eddie (and I do). From what I recall, if I go with larger diameter pipes, my system would get louder (not what I want), I'll lose some bottom-end (undesirable) and gain a bit of top-end (not needed).

 

[celly]

I know you swear by the 3" for a 5.0, but I just want something a little smaller because I do a lot of highway driving and I dont want the drone to drive me wacko. I'll try some of the local exhaust shops and see what they say, and then maybe take the x up to the ones that I like and show them exactly what i want done and go from there.

My local shop pretty much told me the same thing. I just did my first road trip this weekend on my 5.0. Resonation was manageable, but I definitely wouldn't want it any louder.

 

[410Fortune]

my BII is LOUD at most speeds Its a Bronco though so I am not worried about it, the 35's are loud, the rattles and squeeks are loud etc.

A single 3" will flow well and still keep some back pressure for more torque.
Dont forget my truck is modified on the intake and full exhaust.

If you are doing this for noise, get a quieter muffler, not a smaller pipe, that is my point. A single 3" from the muffler back is a great setup for a 5.0L IMO.
In front of the muffler, 3" would be too large, I believe stock is what 2 ea 2" pipes to the secondary cats? thats what I am running to my muffler is the stock Explorer down pipes.

 

[celly]

my BII is LOUD at most speeds Its a Bronco though so I am not worried about it, the 35's are loud, the rattles and squeeks are loud etc.

A single 3" will flow well and still keep some back pressure for more torque.
Dont forget my truck is modified on the intake and full exhaust.

If you are doing this for noise, get a quiter muffler, not a smaller pipe, that is my point.

Flowmaster sort of changed their guidelines, and I quote:

What pipe size should I use for a street application?
In general, the following guidelines should be applied for street applications.

2"
tubing
up to 100 hp per pipe

2.25"
tubing
up to 160 hp per pipe

2.5"
tubing
up to 200 hp per pipe

3"
tubing
up to 300 hp per pipe

This would seem to suggest 3" as well.

(Source: Flowmaster)