BruceH

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doctorstrobe

Hi, here's the notes from the Whipple install guide about boost levels and exhaust upgrades:

BOOST LEVELS
All Whipple kits are shipped with approximately 6.5psi (non-intercooled) and 10psi (intercooled) pulleys for stock
engines (@ sea level). Additional pulleys are available for lower and higher boost levels, although higher boost levels
will void the SC warranty and may need custom PCM calibration. With proper PCM calibration, the factory engine has
proven to withstand 8psi (non-intercooled) and 11psi (intercooled) before detonation on 91-octane fuel. Engines with
other aftermarket upgrades may see slightly lower boost levels due to increased engine airflow. Whipple does not
recommend exceeding 12psi of boost on stock engines without use of race gas.

CAT-BACK EXHAUST SYSTEMS
Whipple recommends a good high flow cat-back exhaust system such as Ford Racing, Borla, JBA and many others.
Typically, cat-back exhaust systems do not increase the total power output, but typically lowers the exhaust back
pressure. This lowers the overall heat the exhaust creates and decreases the overall boost level. In order to see an
increase in power, you typically need to go with a smaller SC pulley to get the boost level back up to the previous
boost level, which equates to more total power.

EXHAUST HEADERS
A good set of exhaust headers have shown slight increases in power output depending on the application. Headers
will also decrease back pressure, which typically lowers the boost level. Most notably, they typically decrease under-
hood temperatures and consequently, give the potential for more reliable power. The drop in back pressure decreases
heat and helps produce more power. As with the cat-back, the more noticeable gains can be seen when the boost PSI
drops and you change the SC pulley to increase the boost PSI back, which gives you more airflow and nets more
power.

Jersey Stang

There was an article in 5.0Magazine.com that compared 7 Long Tube headers on a Saleen 11psi car. The article shows the engine PSI drops by 0.5psi, but total horsepower will increase up to 40rwhp. Sorta negates the whipple article posted above. Anyway, its an interesting read, click above.

Big Top Gt

I think we've all been doing this long enough to know that headers with a boosted application are going to net a significant gain.

I want long tube headers and an H pipe, but I've got two things holding me up.

1. I'm too cheap to spend 1000+ dollars on parts I used to pay less than 300 dollars for.
2. I struggle with the gain in exhaust volume. I don't want a loud DD.

If you're not concerned with either of those things, you should do it.

mikeysGT

not sure about SC or Turbo applications but i picked up some nice numbers with my nitrous setup.

MustangGT0405

You didnt mention which Headers you were thinking about, but I would say forget shorty's or mid's since I dont think they are better enough than stock to be worth it. From what I have read the stock headers dont flow too bad.

So assuming you want LT's then I say they might be worth it depending on your goals. If you ever plan on forging the motor than I say go for it as you will need them later anyway and the boost now is good too. If you never plan to forge and you already have a SC than a smaller pulley will net more power for way less money and the weakest link of the engine is you limiting factor. So you are better off to just run 10psi and be done with it IMO.

I thought about LT's for a while but decided to wait for my engine build to do it. Good luck

onederful100

i already had the LT's when i put on the SC, so no #'s from me. but i do have a friend w/ a whipple terminator and he had 595 rwhp @ 17 psi w/ only borla catbacks. he added BBK LT's and o/r x pipe and picked up 10 rwhp and dropped to 15 psi. if he were to up the boost to previous level there would be significant hp increase. i think it is better to have less psi and slightly more hp, more engine efficiency. i do have the 10 psi pulley but only see 9 psi on the gauge, and i have BBK LT's and o/r x pipe w/ M80 mufflers, and the rwhp is 460.

BruceH

Thanks for the responses. I changed the mounts yesterday and decided to do something different for my next mod. I just figured if I was going to jack the motor up anyway might as well do headers and save some effort.

BTW the car feels tighter with the prothanes. Like the chassis is stiffer. Glad I did this mod.