I will probably add the x-pipe with cats to my 2003 GT but not change the factory mufflers. I am curious about the headers though. Will I lose low end torque if I went with long tubes? I have heard I would have to change the gears to at least 2.73's to make up for the loss in torque down low.

 

2.73's are usually stock gears on 5.0's - and the lowest you can get, 3.27's were used on the 4.6's. Longtubes will likely not lose any torque, but if they do it will be at a very low rpm - below 2k. I've seen a few posts about this at misc. places, and dyno results were included in the conversation. Of course dyno runs usually aren't started until 2500 rpm, but I have yet to see a car produce less low end torque - ever - but then again I can't vouch for sure at the lower rpm ranges. Peak and average torque will definately increase.

I think the reason most people think long tubes reduce torque is because of the old addage that less exhaust restriction = less torqu, more hp. Longtubes also help with cylinder scavaging which will increase low end torque - and will likely offset any loss in torque from the decreased backpressure. Also the top end power increases considerably by the ole SOTP meter - probably causing the perception that you lost something down low - when it fact you lost nothing down low and only gained up top.

Thats my .02 on the subject - let me know if you want change.

 

My mistake I did mean 3.73's since I knew it came with 3.27's.
I do understand the sotp meter and scavanging and I've learned a lot from the exhaust I have on my truck. I guess in most cases I will probably be above 2000rpm.

I like the x-pipe with cats because I hear it gives the best performance and I need to be able to be inspected (although the H gives the best sound). I hear mid pipes a lot when speaking of long tubes. Does the mid pipe go between the xipipe and the long tube, kind of like the old down pipe but shorter? What's the consensus on good long tubes, mid pipe and x-pipe? I was looking at the bassani x-pipe but I think I may try to go to a Mustang event and just listen till I find the sound I really like.

Is anyone running long tubes and 3.27's are is it a given that I'll have to go to 3.73's with the long tubes?

 

I ran longtubes before I did gears. They made a noticable sotp difference and nothing but more power everywhere (I did the whole exhaust at the same time). The mid-pipe is the x-pipe (or h ). You will need a shorter one for use with the longtubes, since longtubes extend down to the bottom underside of the car instead of just off the headers.

SO no, you don't have to go with a higher gear to run longtubes, you'll have more torque through your operating range, and down low you likely won't lose anything - even at idle.

 

you wont lose any low end torgue, unless you choose to big of tubing or have to big of exhaust piping for your cars hp. its all about exhaust gas velocity. bigger pipes dont=bigger hp

 

ok, I'm in!
Will start looking for long tubes, cat'd x-pipe, 3.73's and plenum.

Race1

 

Stay with long tubes no bigger than 1-5/8" diameter and you won't have to worry about any loss of low end torque at all. Anything larger than this will not add anything and will hurt the low end performance.