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What HP level is the factory exhaust restrictive?

silverboost

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I'm doing a whipple stage II build on my ordered F150 RCSB and looking to understand at what HP levels is the factory muffler and tubing restrictive? Given that aftermarket exhaust are very limited still for 2021's and the prices of aftermarket is sky high. Wondering if it's more sensible to just replace the muffler and keep the factory exhaust tubing if it's not restrictive.
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You're spending about $9000 and you're worried about the price of the exhaust? Don't get cheap now, lol.
I would think at the very minimum removing the resonator and stock muffler would get you some gains. You're going to be sucking in a lot more air than stock and its going to need somewhere to go.
 
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silverboost

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It's not so much the cost but really the limited exhaust options for full cat backs.
 

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Watch Mizer brothers Backroad Driver vids they went through several exhaust iterations on the Gen13 Supercharged Wolf (750hp) and are waiting for blower and tunes to be available for Sam's 2021. Soon? ECU is still not cracked so likely will need bypass until it is. Plus Roush has systems. Gen13's can be fit to Gen 14 also. (See Sams 2021 retro fit vid) I think at 750hp and $10k+ its no longer about 10 more hp but not grenading the whole drivetrain. LOL i.e. see latest vid on fixing the missfire.
 
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silverboost

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I've already pre-purchased my Whipple kit through Lethal Performance and Whipple themselves are in the final stages of finalizing their tunes. Kit's should be starting to come out around mid-July with the whipple tunes. I probably won't even have my truck by then, but I am already ordering everything now so when it does arrive I can start with my upgrades immediately.
 

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AFE’s cat back bolted straight up to my 21
 
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silverboost

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Do you have any sound clips of it? I want something more throaty but not drone on the highway.
 

agentorange

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You're spending about $9000 and you're worried about the price of the exhaust? Don't get cheap now, lol.
I would think at the very minimum removing the resonator and stock muffler would get you some gains. You're going to be sucking in a lot more air than stock and its going to need somewhere to go.
Watch Mizer brothers Backroad Driver vids they went through several exhaust iterations on the Gen13 Supercharged Wolf (750hp) and are waiting for blower and tunes to be available for Sam's 2021. Soon? ECU is still not cracked so likely will need bypass until it is. Plus Roush has systems. Gen13's can be fit to Gen 14 also. (See Sams 2021 retro fit vid) I think at 750hp and $10k+ its no longer about 10 more hp but not grenading the whole drivetrain. LOL i.e. see latest vid on fixing the missfire.
750 hp is a good problem to have. The 2021s will be limited on power and speed. Thanks Ford.
 

agentorange

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I'm doing a whipple stage II build on my ordered F150 RCSB and looking to understand at what HP levels is the factory muffler and tubing restrictive? Given that aftermarket exhaust are very limited still for 2021's and the prices of aftermarket is sky high. Wondering if it's more sensible to just replace the muffler and keep the factory exhaust tubing if it's not restrictive.
I'm also going that route, but I'm a little skeptical because Whipple has told me they will not sell me a 3.8l version and the speed will be limited to 125mph.... Safety reasons they say. I say, If I'm worried about safety, why would I buy a supercharger? Also, let me worry about me.
 
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silverboost

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I'm also going that route, but I'm a little skeptical because Whipple has told me they will not sell me a 3.8l version and the speed will be limited to 125mph.... Safety reasons they say. I say, If I'm worried about safety, why would I buy a supercharger? Also, let me worry about me.

What limited to 125 mph? First I am hearing of this and if so that sucks. It won't be long though before other tuners are able to tune. Hopefully there we will be able to lift the restriction.
 

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agentorange

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What limited to 125 mph? First I am hearing of this and if so that sucks. It won't be long though before other tuners are able to tune. Hopefully there we will be able to lift the restriction.
I hope so.
 

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It's not so much the cost but really the limited exhaust options for full cat backs.
You need to go full dual exhaust.
You are adding a blower.
Any shop can install a dual exhaust system.

You need to flow much more air than the 2 into 1 can handle.
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