[stumpjumperpro]

I bought my 07GT a few months ago from a guy who started to mod it. The car has:

Magnaflow 2.5" CatBack Exhaust w/Magnapacks (15883)
UPR Off-Road X-over Pipe (UPR-7000-05)
and some other stuff...

I ordered some stuff from Steeda today. The guy told me that not having cats would make me lose torgue. He said it would run great flat-out, but I am losing torque on take-off. Is this true? If so, I would rather have take-off torque than flat-out speed. Should I go back to a Magnaflow high-flow cat X-pipe to regain torque?

 

[04KenneBellGT]

Ive never heard that before. The only problems i hear with off road pipes is inspections. I thought it gave ya a couple more horses, figured it would be the same way with your torque.

 

[bmw2stang]

A guy at the tuner shop I go too said the same thing about losing low end torque.He said it loses back pressure to the point of losing the take off torque and he said he recommended one with high flow cats.

 

[stumpjumperpro]

Yea, he said that a ricer could beat me off the line pretty easy with the torque lose. I guess there goes another $500 for a high-flow X-pipe.

 

[Troon2004]

I'm not certain you lose all that much torque via what you described: maybe someone who's done the dyno comparison between stock and a set up like yours would know/be able to shed some real light on the subject.

Also, these vehicles have oodles of torque to begin with at the low end in comparison to most any (if not all) of the stock vehicles you're referring to so I don't know that you'd be at much of a disdvantage (if you want to call it that) running your set up as you might otherwise think/be concerned about.

 

[exospawn]

Here is a good page that explains how exhaust works. how and why certain myths about exhaust creating/reducing power are myths.

Exhaust Theory

 

[Troon2004]

Really great post- I always appreciate someone who's done some homework and shares it here. :bigthumbsup

 

[Silverstang07]

it IS true that you lose a LITTLE take off torque, but you gain elsewhere.......i personally dont think my car will ever see a cat again.

 

[blk281gt]

I just switched to an off road x last weekend (pypes) with Mac axlebacks.Did not notice any different low end and probably pulls a little harder. Smell is not that bad, but definetly there. A little to raspy for my liking now so i have more mufflers coming today (pypes street pro).

 

[stumpjumperpro]

Cool, thanks guys. I am running stock gear now also, 3:31 I believe. I will be going to 3:73 more than likely in case I go supercharged later on. I had 4:10 in my 01 Bullitt and it was a beast stock. At least for my liking.

 

[tached_out]

the amount of loss that would happen would not make a difference. I doubt removing your cats will make a ricer that you use to pull of the line be able to get you off the line.

I run cats for the street just because with LT's it would my exhaust EXTREMELY loud but I plan to buy an O/R pipe for the track

 

[88_stanga]

only thing i didnt like about not having cats was standing behind it while it was running. burns your eyes like a mofo

 

[kj_cinci]

I call bull! Sure you may lose some backpressure and maybe MAYBE some low end TQ but the over all gain is much higher!

The muffler work in oposite... restrictive takes TQ while wide open adds some... but then again all is said and done after headers and mid pipes... why run mufflers at all?? No pwer back there... only restriction....

 

[stumpjumperpro]

I think I am convinced to not worry about it. Besides, I love the way it sounds and would hate to take that away ;-)

Thanks everyone!

 

[Troon2004]

The French solution: "off with their head[er]s" unk:

 

[ski]

Go for it. WRT getting good off the line performance, rev it to 3-4K rpm before launching. That puts the engine near its peak torque range. Just remember to slip the clutch. If you have an auto and want high rpm launches, then install a high stall converter.

 

[Dark Horseman]

The way to think about it is where do you want to shift your power curve. I just took off my off road X today to bring more torque down low and sacrifice the mid to high end power shift gain of the X. There is a point in the rpm range where the H joint becomes non-functional. Some who know the S197 well, claim that the max power gain available from the exhaust is a 10 point gain across the range. The restriction point is the stock mufflers. Address the restriction point and choose a mid-pipe that well place your torque where you want it. H down low, X up high.

Initially, I wanted to see what the potential of the stock motor was with bolt ons as a limited experiment of whether I would stay NA. It was fun, but not fun enough. My twin screw is en-route and I want to complement the power adder with a stock H to match the canned programing. X pipe is raspy sounding with power curve shifted high in the range. I don't have any regrets running the O/R X, but it is not a crucial must have on the car, IMHO. Just $.02.