Loss of Power from Headers?
 

My brother has a '00 GT with a SCT tuner, JLT RAI, MAC cat-back, MAC o/r h-pipe, and we just installed some BBK shorty headers. With the headers on now, the car is sluggish down low, like it lost torque from losing back-pressure.
Once he gets going around 50 mph, the power really comes back and it pulls hard. The exhaust also gets deeper and sounds more powerful. With the full exhaustnow, does he not have enough back-pressure? I figured itwould be fine. Has anyone else put a full exhaust on a stock GT and got the same results? What do you think will fix this problem?
Next, to try and fix this, my brother isthinking aboutgetting an Accufab75mm TB/plenum to see if the added intake will bring back some back-pressure. What do yall think?

RE: Loss of Power from Headers?
 

well I dont think installing shorties would give you a significant gain in power, but it certainly shouldnt HURT your total hp/tq numbers. Maybe it feels sluggish down low, like many other exhaust components, due due it efficiency at higher RPM levels

RE: Loss of Power from Headers?
 

shorties offer a different power band than what he's used to, they add hp in the top end at the sacrifice of low end torque...people will say the opposite about long tubes sometimes, because they make low end torque...but he's probably making more than he was before all around atleast...he should try re-tuning with the SCT...but im not one to ask about all that

RE: Loss of Power from Headers?
 

Make sure there are no leaks. Modifications like such generally add HP/TQ all throughout the powerband, however some make a significant difference higher in RPM's & give the illusion that the car is actually slower than before.

There is no aftermarket header offered for 96-04 GT's that will cause any issues with too little back pressure. If you understood how backpressure worked you wouldn't be asking this. :D

RE: Loss of Power from Headers?
 

Well we knew we wouldn't feel a power difference. He just wanted it for sound because he never plans on LT's. While minimal power was expected, we didn't expect to lose any power/torque. I guess we'll just have to see what a TB/Plenum will do.

RE: Loss of Power from Headers?
 

Quoting myself because I guarentee this is the problem.

RE: Loss of Power from Headers?
 

If you read the first post, I did not expect it to be back pressure. LT's on a stock GT would add power and they flow way more than shorties.

RE: Loss of Power from Headers?
 

Huh? You said the lack of back-pressure could be the cause? It's not.

Make sure there are no leaks, otherwise it's all in your heads! You suffered no TQ loss. TQ was increased down low & up high, however the increase in TQ higher in your powerband will give the illusion that the car is slower down low than before.

RE: Loss of Power from Headers?
 

Exactly. I said there shouldn't be a back-pressure problem. Losing a little more than needed back-pressure would reduce torque, but I said I doubted that. We are checking for leaks this weekend. I personally have not rode inor driven the car, I'm just saying what he described to me. I'll tell him it's probably just feeling that way, but its not.

RE: Loss of Power from Headers?
 

Oh sorry about the confusion.

Yeah if there is no leaks, then your buddy just got fooled by the butt-dyno. [8D]