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Discussion Starter · #1 · (Edited)
Did three pulls today. First two were while the car was still warm. Third, the best pull, was after a long cool-down. Best 220 rwhp, and 256.6 tq.

Car is mostly stock 4.6 Auto. Roush CAI, exhaust(flowmaster 1 chambers), 4.10s, and Saleen Powerflash are the only change.

Shouldn't this be putting out more power than that?
 

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Well, I have heard that the flowmasters, even though they sound great, can rob horsepower. That's why I changed mine to a Magnaflow catback. Cant tell you what it's gonna do cause I am having alot of stuf done to the car right now, then its getting dyno tuned. The chip on a stock setup will net maybe 3-5 rwhp, and the cold air should have done a little bit as well. The numbers you posted are the same as what a bone stock GT would put down.
 

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02roush said:
Did three pulls today. First two were while the car was still warm. Third, the best pull, was after a long cool-down. Best 220 rwhp, and 256.6 tq.

Car is mostly stock 4.6 Auto. Roush CAI, exhaust(flowmaster 1 chambers), 4.10s, and Saleen Powerflash are the only change.

Shouldn't this be putting out more power than that?
You can compare it to my #'s and judge for yourself.

My auto put down 237 hp & 281 TQ with mods listed below.
Our only power making mod differences are xpipe & pulleys and we have an appoximate difference of 17 hp & 25 tq.
 

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i love saleens..but the powerflash isnt exactly the greatest tune in the world.
 

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First of all, For a auto those are nice numbers. Next I have to ask why mess up a nice Roush exhaust with flowmasters ? Also doesnt Roush have a reflashed computer ?
 

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Discussion Starter · #9 ·
ROush uses Magnaflow mufflers. THey had no sound till WOT. ALso Roush only changes the computer on the Stage III (supercharged version)
 

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I ran a 228 rwh and 270 torque with only the MagnaFlow side exhaust before all the mods.
By the way I'm new to the board and will post up pics and list mods as soon as I can. Very busy this weekend. Hopefully Sunday!
 

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Hey sonic. Welcome aboard. Quick question, did you gain any power with the magnaflow exhaust, or did it come stock and you dont know?
 

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Discussion Starter · #12 ·
Hey SOnic, is yours an auto or stick?

And are you on www.fnsweet.com ?
 

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Don't know if I lost or gained Horsepower with the Magnaflows since I dynoed it after I had them put on. I would have to say I gained just alittle.
02Roush its a 5 speed Manual and yes I post at fnsweet (sonicblue02)
 

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Flowmasters do not rob horsepower over stock. This has been dyno proven more than once. They are weaker than Dynomax or Magnaflow, but that is a different comparison. To say they rob horsepower would only apply if you were changing from an already high flowing muffler design. I think a more accurate statement would be that Flowmasters detract from some of your cars potential power or simply that there are better designs out there.
 

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Discussion Starter · #15 ·
The car had Magnaflows(part of the Roush side-exhaust) when I first got it. I changed them for the Flowmasters, and it did seem to get a little slower.

But enough to dyno 15 hp under stock? I can't see it robbing 15 hp from the Magnaflows.
 

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No, not at all. First of all, Magnaflow and Flowmaster mufflers dont vary that much when it comes to gain/loss numbers. Some people have even reported a loss in power when using a CAI due to the way it wreaks havoc on the MAF (read:turbulence). Also are you factoring in drive train loss? I have heard that a good rule of thumb is 16-18 percent HP loss through the drivetrain. If you just factor 15 percent loss, that is minus 39 HP to the wheels, which sets you at 221 HP to the wheels. A CAI and chip burn arent going to make a whole lot of difference on an otherwise stock NA car...sometimes none at all.
 

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Discussion Starter · #18 ·
The numbers are rear wheel hp. We figured 20% loss for the Auotmatic loss. Which comes to 264.4 at the flywheel. So is it near where is should be?
 

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That is just about right. And Stanggt00 is correct...if you had better flowing mufflers you would see more power.
 
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