The increase is 17hp and 17tq. I think I can get more out of these headers once the car is tuned; notice the 'big dip' in power on the sheet towards the end. Does anyone know what can cause that to happen and what the correction is?

 

18 hp and 17 tq is very nice!!...my hp #'s were exactly the same with the JPI headers but tq was lower @ 8lbs gain

 

So it's safe to say that headers add 22hp/22tq to the crank. That's great...and just imagine if you get an SAFC and tune your ride. Looking at your signature I don't even see an intake on your car! and your pulling 266whp! Addition of intake and SAFC with dyno tune and you MUST be at 280whp! Great for an N/A GS4XX!!! Awesome news! Keep up the good work! Hey, Lexizm...BTW I am looking into headers as well would you recommend the S&S or the JPI's (when they come out)?

 

He had one on order, but after I put it on my ride and tested it on the dyno......as controlled as you can get. Tested stock. Then with the car still straped to the dyno we installed the intake and the hp and tq numbers went down! We couldn't believe it!!!!! The the company didn't want to give me a refund! If they don't we are going to have major prolems! Until I find out if they will refund me or not I will not name the company. He does have a K&N drop in.

 

Accoarding to 'Speedaddic' you get 9lbs less torque. The S&S headers have the torque and you can most definitely notice it. I do know know that there have been issues with the 1st batch cracking. I know JPI just came out so don't know if there will be any issues with cracking, doesn't look like it. I prefer having the torque (S&S) myself. I only had the headers for a short time.

I do plan on getting a SAFC. That will be my next performance purchase; 280rwhp would be awsome for real.

 

i've seen ignition issues cause a dip like that before. i'm guessing yours is stock, how old are the plugs?

 

that's not very surprising, most of the manufacturers hp claims for intake systems are bull*****. i'm surprised people believe those claims to begin with. BTW i've been way too busy to deal with the exhaust lately, out for work again on monday.

 

Those are some awesome gains!!!

It's like giving your car a new lease in life!

 

I personally feel that if you get an intake WITHOUT an A/F tuning device it CAN be counterproductive with regard to performance.

Without A/F controller
Best to worst

1. stock air box setup w/K&N drop-in
2. air intake system
3. stock air box
4. air intake system w/cold air feed (wheel well)

With A/F controller
Best to worst

1. air intake system w/cold air feed (wheel well)
2. air intake system
3. stock air box setup w/K&N drop-in
4. stock air box

 

we'll find out for sure when I order another intake on monday! I'm getting an account set up with K&N and I'm going to order a fipk. They have a money back guarantee that you will gain hp! you shouldn't need an A|F controller with just an intake! The A|F sensor in you car should be able to compensate for the air gain!

 

are these SAE-corrected numbers from the dynojet?

 

no, they are DIN corrected numbers, which will always read higher than SAE. something to remember if you're comparing this dyno graph with another dyno graph that has SAE correction.

 

Nice work guys & great numbers Its been years since someone has done what you guys did.. Dyno truth or dare before our eyes. I don't want to tell folks "I told you so". I personally went with the K&N drop-in for a reason.. To each his own though, and I respect that.

 

You don't necessarily NEED an A/F controller for an intake and exhaust but it will definitely allow you to squeeze the MOST HP/TQ out of your setup...

 

Well the dip happens in both runs before and after. I have noticed many modern engines having a "restricted" feel at full throttle. A friends Chrysler 300 HEMI felt very restricted doing runs with my GTech Pro Competition (btw, his ran 5.9 0-60 and my LS400 ran 6.0 0-60 back to back with both of us in each car for each run).

The dip is most likely due to the knock sensors pulling timing. This is not necessarily due to actual detonation detection but may be a resonance issue. It is always a good idea to make certain you have good fuel in the car for measuring performance. That said you should of course run any before and after testing on the same fuel.

Some systems allow you to view exactly if timing is being pulled. Our Toyota/Lexus systems are not well supported in the aftermarket and I am unaware of exactly what data can be checked and or what equipment would allow checking.

If the dip happened only in the after then we could make some other guesses but since it is in both pulls it will remain unanswered unless we can get some specific computer data.