Exhaust guys, help me out!
04-06-2016, 01:39 PM
#1
Exhaust guys, help me out!
Hello everyone, quick question. Kinda simple but I'm just checking before I do anything.
2001 f150, scab.
Currently : SI/DO - flow master muffler, stock 4 cats.
Wants : Delete all 4 cats, replace with 2 hi-flo cats, convert from si/do to true duals.
In my head what I'm thinking is if they take off 4 cats and have to replace them, would it not be possible to simply make it true duals? One shop said it would be around 600$ (would take out all 4 cats, replace the rear 2, mufflers, tips blah blah) another one said No?
So question is, is that correct ? Replacing the rear 2 cats, running 2 pipes into 2 si/so mufflers to tips. Any help is greatly appreciated. And yes, i know the laws with cats and the fine for removing them, inspections, blah blah. Please don't spam the post with that like I have seemed to see in every other exhaust post.
Thank you all!
- Mike.
2001 f150, scab.
Currently : SI/DO - flow master muffler, stock 4 cats.
Wants : Delete all 4 cats, replace with 2 hi-flo cats, convert from si/do to true duals.
In my head what I'm thinking is if they take off 4 cats and have to replace them, would it not be possible to simply make it true duals? One shop said it would be around 600$ (would take out all 4 cats, replace the rear 2, mufflers, tips blah blah) another one said No?
So question is, is that correct ? Replacing the rear 2 cats, running 2 pipes into 2 si/so mufflers to tips. Any help is greatly appreciated. And yes, i know the laws with cats and the fine for removing them, inspections, blah blah. Please don't spam the post with that like I have seemed to see in every other exhaust post.
Thank you all!
- Mike.
04-06-2016, 02:55 PM
#2
Senior Member
Since you have no idea, - being you left out the most important part running a system like this (for your truck anyway). I won't say much.
Anyway,
Anyway,
04-06-2016, 03:10 PM
#3
Junior Member
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Hello everyone, quick question. Kinda simple but I'm just checking before I do anything. 2001 f150, scab. Currently : SI/DO - flow master muffler, stock 4 cats. Wants : Delete all 4 cats, replace with 2 hi-flo cats, convert from si/do to true duals. In my head what I'm thinking is if they take off 4 cats and have to replace them, would it not be possible to simply make it true duals? One shop said it would be around 600$ (would take out all 4 cats, replace the rear 2, mufflers, tips blah blah) another one said No? So question is, is that correct ? Replacing the rear 2 cats, running 2 pipes into 2 si/so mufflers to tips. Any help is greatly appreciated. And yes, i know the laws with cats and the fine for removing them, inspections, blah blah. Please don't spam the post with that like I have seemed to see in every other exhaust post. Thank you all! - Mike.
04-06-2016, 03:38 PM
#4
The system I have now, isn't as loud as i would like it. So trying to delete hear cats, was thinking why not switch to true duals while everything is off.
04-06-2016, 03:40 PM
#5
04-06-2016, 04:23 PM
#6
Senior Member
I personally don't think you'll get anything in return for your money. As I recall, you'd have to run it up the passenger side. I'd stick to a SI/DO muffler.
For giggles, here's a couple quotes I've got bookmarked from an old Hot Rod Mag.
For giggles, here's a couple quotes I've got bookmarked from an old Hot Rod Mag.
Borla says:
"There is no easy answer, but as a basic rule, if the car is used for your daily driver, and/or if it has a fairly stock engine, you'll be happier with a smaller (such as 2 1/4-inch) system. The performance you'd gain with the larger system usually isn't worth the loss of better sound quality. However, if the engine is very built-up, and if you race it on the weekends, you may want to reap the benefits of the larger and louder 3-inch system."
Flowmaster says:
"This is the age old question: Power or sound control? Flowmaster doesn't recommend 3-inch for street use because of the sound legality side of things. Basically, a 400hp engine is quite happy with 2 1/2-inch exhaust. It doesn't matter if it's blown or nitrous fed as long as it doesn't make over 400 hp. If you're going to be much over this in the way of power (i.e. if your base engine is 350 hp, but the bottle drives it up to 500 hp), you will likely need 3-inch duals. The bottom line on power enhancers is, how much of the time will it be run in this mode? If it's very limited use, stick with 2 1/2-inch and enjoy the sound.
As for engine size versus exhaust size, the engine is an air pump. If a 350 engine produces 400 hp at 6,000 rpm, it has "X" air and exhaust flow. A 454 engine producing the same 400 hp at a power peak of 5,200 will be flowing the same air and exhaust flow (within a few percent). Therefore, the exhaust flow requirements between the two engines are the same even though the 454 is a larger cube engine."
DynoMax says:
"A common misconception is that the larger the diameter the better the system. But, bigger isn't always better. Systems that are too large in diameter can actually hurt performance. As a general rule (when not running a high compression ratio, nitrous, and/or a blower), switching to a performance exhaust system that is 1/4- to 1/2-inch larger than stock will provide you with the best horsepower increase. To determine which pipe diameter will be best for your system, decide what rpm range your engine will operate at most of the time. Smaller diameter pipes will usually produce better low- to mid-rpm torque. Larger diameter pipes usually produce more mid- to high-rpm torque."
"There is no easy answer, but as a basic rule, if the car is used for your daily driver, and/or if it has a fairly stock engine, you'll be happier with a smaller (such as 2 1/4-inch) system. The performance you'd gain with the larger system usually isn't worth the loss of better sound quality. However, if the engine is very built-up, and if you race it on the weekends, you may want to reap the benefits of the larger and louder 3-inch system."
Flowmaster says:
"This is the age old question: Power or sound control? Flowmaster doesn't recommend 3-inch for street use because of the sound legality side of things. Basically, a 400hp engine is quite happy with 2 1/2-inch exhaust. It doesn't matter if it's blown or nitrous fed as long as it doesn't make over 400 hp. If you're going to be much over this in the way of power (i.e. if your base engine is 350 hp, but the bottle drives it up to 500 hp), you will likely need 3-inch duals. The bottom line on power enhancers is, how much of the time will it be run in this mode? If it's very limited use, stick with 2 1/2-inch and enjoy the sound.
As for engine size versus exhaust size, the engine is an air pump. If a 350 engine produces 400 hp at 6,000 rpm, it has "X" air and exhaust flow. A 454 engine producing the same 400 hp at a power peak of 5,200 will be flowing the same air and exhaust flow (within a few percent). Therefore, the exhaust flow requirements between the two engines are the same even though the 454 is a larger cube engine."
DynoMax says:
"A common misconception is that the larger the diameter the better the system. But, bigger isn't always better. Systems that are too large in diameter can actually hurt performance. As a general rule (when not running a high compression ratio, nitrous, and/or a blower), switching to a performance exhaust system that is 1/4- to 1/2-inch larger than stock will provide you with the best horsepower increase. To determine which pipe diameter will be best for your system, decide what rpm range your engine will operate at most of the time. Smaller diameter pipes will usually produce better low- to mid-rpm torque. Larger diameter pipes usually produce more mid- to high-rpm torque."
04-06-2016, 04:37 PM
#7
Senior Member
They aren't tuned for it. You'll definitely need a custom tune for a trash the environment set up... ie cat-less.
IMO, - high flow CARB compliant cats w/diameter reductions after the Y is a better set up. Plus you won't have to mess with the tune. Definitely loose the mufflers you have listed or they will cut into your part throttle response performance. Go with straight threw design vs a constipated one.
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04-06-2016, 04:51 PM
#8
Senior Member
If you like the welded muffler sound, a much better flowing muffler is the MAC Flowpath. I have one of their first cat-backs they made on my Mustang, and it's a wonderful sound.