Headers + Exhaust = Loss in Torque

Without taking my baby to a local dyno, I noticed that I lost an amount of low-end torque after installing the new headers and exhaust. The exhaust was changed out first (I didn't notice a loss), then the headers came...and the torque left. She no longer burns out as much off the line (which is decent for practical purposes); however, I can't help but feel that maybe the headers weren't such a great idea for the moment. Perhaps I should have waited until I installed the intercooler, or maybe the max torque just shifted to higher rpms. Any thoughts?
I was also wondering about switching to a 3.0" pulley system before I received my intercooler. I'm fairly apprehensive about doing so; I fear the knock may be a bit great. At the same time, I don't have a PowrTuner to adjust my PCM for the upcoming mods. I'm going to list the mods I have planned for the next few months. I would also like input about the order in which I do them (the order I list is how I plan):
(1) 42.5 lb injectors (2) ported throttle body (3) intercooler (4) 3.0" sc pulley (5) send in PCM to be retuned

Thanks for all the input! This is my first post on AF.

First, with how many mods you are running and planning, you need a tuner.

Second, I think you can probably run the 3.0 now. Do you have a scanner that can monitor KR? If you have a modular pulley system, throw the 3.0 on and just keep an eye on KR.

Finally, I bet your mid to top end is great though! I wouldn't of waited for the IC to put on the headers.

Have fun!

I have yet to get a scanner. Could you recommend me one? Thanks for the reply :)

Hmmm, I use a LS1M which was made by one guy that developed it himself.

He's transitioning the production of the needed parts, a Palm pilot, a special OBDII cable and software to some speed shop that he has yet to name.

I bought mine off of a classified section of another board. I can't post it, but if you PM me, I'll give you the URL.

I'm not sure about other scanners, but there has to be a few out there. I can't believe you've been running that heavily modded w/o scanning! That's dangerous!

Haha. No worries. I bought this car 3 weeks ago. I did the headers and exhaust. The car was tuned for them before the purchase. At this point, I'll need tuning equipment.

Ahhh, that makes sense then! Headers and an exhaust only make the car's KR reduce anyway!

I PM'd you.

My thoughts exactly. I wasn't worried about those two mods at all. I am apprehensive about the 3" pulley though...those are scary numbers to get into (- 3")

Headers are always a great idea if you get the right ones. IMO you should have gone with either SLP or TOG brands. Pacesetter headers look good on paper but there are certain design aspects that I don't like and they deviate from the norm like the 1 3/4" primary tubes and collector design. Which may explain your low end power loss. You get what you pay for.

I would not run any smaller SC pulley without seeing where you stand on knock retard (KR) as pointed out. I use the AeroForce Tech Interceptor Scan Gauge and Autotap on a laptop as a backup.

I forgot about the AeroForce Interceptor guage, that is an awesome monitoring tool!!!

Yeah, Pacesetters have documented flaws to include not only the ones listed above, but a common leak at the Y junction. You should see if that is leaking there, the only known sure fix for that is to weld it though. People clamp them, but that doesn't eliminate the leak, it only minimizes it.

Thanks for the input. I ordered the headers from ZZP. They fixed the leaking Y-pipe before sending the headers to me. I'm going to be looking around for those scanning tools. Though, I been reading a bit more on the PwrTuner by DHP; they claim that their tool can also detect problems (not sure if that includes KR...I'd assume so).

They really only minimized the problem with the Y man. Because what they do is actually widen (stretch) the pipe to make a better seal, not a perfect seal. Like I said, the only sure way is to have them welded.

I've heard nothing bad about the DHP either. Everybody seems to like it!

Though, I been reading a bit more on the PowrTuner by DHP; they claim that their tool can also detect problems (not sure if that includes KR...I'd assume so).

The Powrtuner is a highly recommended tuner/scanner. It is pretty costly though, but if you want to monitor KR and other important engine variables while being able to tune your engine and get the most out of it. Of course there are other tuners out there; you cant go wrong with the powrtuner.

As long as your PCM isnt locked, you will be able to modify it. You can even flash your stock PCM with a performance file and achieve the same effects as switching it out. Someone please correct me if I am wrong but I thought I heard that DHP PCMS were locked and unable to be tuned. ZZP offers performance PCMS that are NOT locked and can be modified by anyone.

Also, as mentioned before the Aeroforce Interceptor scan gauge kicks arse. I will be buying that as my 2nd gauge to complement my boost gauge. You can view dozens of variables, switch between variables and clear codes, however it lacks the tuning ability. That is where the Powrtuner comes in, it can monitor and tune. You could be elite and get both :sunglasseI would recommend putting in for overtime though :grinyes:

I don't recall the DHP v1.0 PCM being locked as a matter of their general policy. They do have some issue about reflash protection in the event of dealer overwrite. It was called "Re-flash Guard". See below. Therefore, you should be able to program with the DHP PowerTuner. The files floating around are called BIN files and caution should be used when using someone's elses. IMO you are better off starting scratch but with some basic and advanced knowledge of what you are getting into. Here is a link to one of the best tech articles around using a PowerTuner. Scroll down to custom PCM tune and he has several pages explaining areas such as "Torque Management", etc.

http://74.57.209.83:9000/pcm.htm


This provides for one re-flash to your PCM with the code purchased in the event of code overwrite (i.e. Dealer Re-flash). The unit returned MUST be the same as purchased and accompanied by ALL of the following 3 items below. Failure to provide any/all of the requirements will result in a returned unit including shipping charges incurred:
1.) Digital Horsepower Inc. inventory sticker
2.) Copy of your purchase receipt
3.) Full name, address, phone number of original purchaser