Headers should I or shouldn't I....Need Advice Quick Please
 

Ok guys I got my car to a 13.90@98 pretty much stock, gears pulleys and a short belt, now the question is on exhaust. I've got a set of equal length shorty headers I've had them for a over a year and I'm thinking about throwing them on. My car is running the stock exhaust out the back right now, including 4 cats and factory mufflers.
If I say go with a 2 1/2" X-pipe and 2 1/2 inch flows and dump them at the axle along with those headers is that going to be too much and slow me down. My big concern is the headers, this motor is completely stock except for the pulleys and I've heard reports that without enough back pressure on them that it's going to slow me down.
I saw a dyno test on the web one time where they did a test with all the popular bolt ons including headers and an X pipe or H pipe on it and I can't find it anywhere. It seems like the headers were only really good for 3 hp and actually lost like 2 hp on the low end.
I'm getting ready to spray it 100 horse and I don't want my exhaust holding me back but at the same time I don't want to loose any power from all motor runs.
Thanks for any information, and if anybody knows where that dyno test I was talking about was online I'd appreciate it greatly if you could post a link.

I have the exact set-up you are wanting.....when my engine was stock I put on my 1 5/8 equal length BBK headers and got 2 tenths slower.

If you are going to add headers to a stock engine 1 1/2 unequal lenght shorties are best.

Hope I helped...
Later,

hey dark 5.0 what mods would make the equal length the better choice

If you plan on running Nitrous/power adder.... or with heavily ported or aftermarket heads the 1 5/8 equal lengths would make more HP.

Long tube headers perform even better than equal lengths do...but to me they are not worth the trouble to install.

Later,

I think longtubes are the way to go, i heard they are hard to install, and i've heard they aren't?? taking the steering shaft out doesnt sound fun to me, but im gonna try it soon i hope, imo, Lt's work well with a stock headed mustang, with pullies, gears, roller rockers, and little stuff, im sure it could lose torque, i think you can get 1-1/2 Lt's also, which can make good power even with heads and cam i would think, nos loves longtubes, even a small shot.

Spraying the nitrous you will pick up some HP with the 1 5/8 BBK headers that you have and they may or may not slow you down all motor.

Of course long tubes are the best way to go, but since you already have the BBK equal length headers I would just install those.

I know people running 10's with BBK equal length headers. Also they look awesome under the hood.

Later,

Well long tubes are something I'm not going to get in to, they can also cost you some low end due to loss in back pressure, been there done that on other cars. They're not really all that bad to put on but at this point I don't really need them and wasn't wanting to go that far. I think I'm just gonna go with the manifolds for now and work on my suspension.
I found the dyno test btw from an old Ford Magazine from 97, it had all the popular bolt ons, they lost .7 foot pounds of torque at low end and gained 3 horse power at the top end. I don't think it's worth the trouble at this point so I'm not gonna bother with them for now. If I spray it and it doesn't do like it should then I'll probably throw them on.
Well thanks for the info guys, I got a 75MM Pro-M for pretty cheap the other day and put it on today, I guess I'll find out if they really do anything on a stock motor tonight at the track. The dyno sheet says 3 HP.....we'll see in my trap speeds.
Thanks again for the help.

I would go with the headers and the h or x pipe along with a good cat-back if your are going to spray any amount of n2o because the stock ex. system sucks and the back pressure can cause a blow head gasket/s depending on the age of the head gasket and if you plan on doing more mods(which if your on this site you have same prob we all do WE WANT MORE POWER AND MORE AND MORE) I would install the full ex. system but that is just what I think(the head gasket that came from all these mags on stock fox stangs n20 intalls and dyno / 1/4 runs

I had the 1.5" EL shorties on my car when stock. It pulled 237rwhp (not a monster, but that was basically stock with some pulleys...).
I kept these headers on even with the S-trim for a while...

Now I finally stepped up to 1-5/8" longtubes for my new 500hp motor combo.

I am always an advocate for smaller primaries and "...Luke, use the torque..." (aka Star wars). :D