..power gains from headers...weak or strong?

Getting SLP Longtube headers with no cats and SLP loudmouth exhaust, anyone have any idea how much of a power gain that is without dyno tunning the car? Anyone......now it openeds up the conversation wether or not I want the blower or a cam....

Headers are generally good for 20 hp give or take a few. Almost any catback system is good for another 5-10. You do the math. ;)

If you are going to go with no cats, I suggest gettin a catback with a muffler.... going with a loudmouth your car is 1. going to be way too loud and 2. wont have any back pressure (its going to be sluggish in lower rpm's). I took out my cats last week and opened my cutout and it sounded like a drag car.

Did your SES light come on when you put on your headers?

havn't put them on yet, but I am hoping if I am making the wrong descision that someone at some point would let me know, I am putting the SLP longtube headers and I am putting the SLP loudmouth exhaust which is a cat-back exhaust.

haha get a muffler....it'll be way too loud

or stock cat back and have a cutout in there :D . silent when you want it, loud when you want it

The SLP long tubes are good for about 20-25hp on a mildly modded car and the Loudmouth is usually good for about 15. The sound isn't to bad with cats but your car will be LOUD if you go with the offroads. The offroad pipes that we sell for these headers come with 02 simms so you won't have to worry about the SES light.

Tom

i have that set up, only i have cats (im going to take them off soon) and yes it is too loud, im thinking of putting the duel duel back on to quite it down

Originally posted by 35thanniv.SS
I took out my cats last week and opened my cutout and it sounded like a drag car.

Was it hard takin the cats off. Can you do it yourself, as in are they bolted or welded on.

Originally posted by 35thanniv.SS
2. wont have any back pressure (its going to be sluggish in lower rpm's).

I don't know where you get you info but fyi, any back preasure is bad. You want zero backpreasure.

Originally posted by Aklaim
I don't know where you get you info but fyi, any back preasure is bad. You want zero backpreasure.

Well, you want 0 backpressure for top end horsepower, but usually need some backpressure for bottom end torque (which is nice to have for street use). That's where you get the 'sluggish' feeling. Depends on your end goal.

i got 23 rwhp from my flp long tubes:D no cats

i just performed the slp longtube swap on a car that already had a loudmouth system on it. the job took about 10 hours for the headers and was very noticable. just driving, it's not that loud, get on it a bit and everyone around you will know it. going to replace the hollow resonator in the loudmouth with a bullet. he is right, zero backpressure is what your going for at all rpm. quite often a larger exhaust will have a negative backpressure down low causing lower velocity which is where the low end torque goes down. as the rpm goes up the the velocity goes up, the exhaust will then go to zero or low positve backpressure and stop sucking the intake air charge out with it. btw, on the car i performed this on, it is an 02' SS M6 with slp lid, 85mm mass air flow sensor, smooth bellows, longtube headers (with matching cats), loudmouth catback, 4.10 gear, and programming by ed wright (only non slp part).

Yeah I got the slp headers with the off road kit hooked on to the loudmouth. When I got it done they said it is loud, So I said ok but they didn't tell me it was as loud as a prostock car. I noticed it felt very weak at low rpms and you can be heard for two- three miles when you get on it and a hlf a mile when you crank it up. I put the cats on I found that it had more pro's then cons better backpressure, quiter, more low torque, and you don't break any federal laws. The two cons were that I would sacrafice 2 rwhp and i couldnt make it a flame thrower. my times were still the same no loss no gain. You even out.

signature

YYESSS...I like it loud, I have a Flowmaster 80 series and I wanna drive and piss people off at the same time, help's me avoid the accidents with the old people saying they didn't hear my car or they didn't see it....but no, really I like noise, but I mean i don't want it to be noisy I want it to have some more power, i greatly appreciate all the responses you guys gave me, good stuff......

havn't put them on yet, but I am hoping if I am making the wrong descision that someone at some point would let me know, I am putting the SLP longtube headers and I am putting the SLP loudmouth exhaust which is a cat-back exhaust.

There are a lot of people that will tell you are making the wrong decision but very few of them own slp lt’s. They are a good deal considering they least expensive stainless/coated header you can buy. I own them and like them. I have no dyno numbers yet but they made a sotp difference.

O yeah below is my first post on this sight.

Slp’s gain the same as the other longtubes on the market which is between 15 and 25 rwhp on an otherwise stock motor. I’ve seen all types of headers with all types of different dyno results but you can expect a track gain of 2.5-3mph and .2-.3 tenths off the quarter.

Slp’s are frequently bashed for their low clearance but they are great quality header. They are the least expensive stainless and coated setup you can get.

Gm high-tech dynoed an A4 trans-am with a lid, zo6 intake, catback, and Slp headers with catted Y-pipe and got 347.7hp and 347tq. These are great numbers considering the car was an A4 with a stall and a catted Y. A typical a4 with all the above mods (minus the headers) would probably hit a max of 325rwhp, so you could probablly conclude the headers were worth around 22rwhp.

a gear swap has a remarkable way of sorting out low end sluggishness.

The loudmouth + longtubes+ offroad y will be very loud, and you may want to reconsider either 1) using cats or 2) the choice of catback exhaust... UNLESS your fbody isn't your everyday car, in that case you'd only be driving it for pleasure and who cares how loud it is.

Yes I know catalytic converters are expensive... but not any more expensive than a new exhaust system.

:lol:
YYESSS...I like it loud, help's me avoid the accidents with the old people saying they didn't hear my car or they didn't see it....


I'm not endorsing any name brands but the mods in the sig make a significant difference.

YYESSS...I like it loud, I have a Flowmaster 80 series and I wanna drive and piss people off at the same time, help's me avoid the accidents with the old people saying they didn't hear my car or they didn't see it....but no, really I like noise, but I mean i don't want it to be noisy I want it to have some more power, i greatly appreciate all the responses you guys gave me, good stuff......

If you really like loud put a cutout before that 80 series. :cool: The 80 series muffler is not a high flow unit so you would also pick up decent hp.

i see all the info on the loudmouth but does anyone have no cats with tsp rumbler? too loud also?

Well, you want 0 backpressure for top end horsepower, but usually need some backpressure for bottom end torque (which is nice to have for street use). That's where you get the 'sluggish' feeling. Depends on your end goal.

LS1's need SOME back pressure to run right. Not talking 2" exhaust. But wide open headers and a 4" exhaust is over kill inless you're running big #'s and a lumpy cam.

I'll be happy with my SLP LT's and catted Y,When I get them installed, MAY BABY!!!....I'm listening too...Thanx for the words..:thumb:

i just performed the slp longtube swap on a car that already had a loudmouth system on it. the job took about 10 hours for the headers and was very noticable.


I thought a headers were a 2 to 4 hour job, not something that took all day and then some.

I thought a headers were a 2 to 4 hour job, not something that took all day and then some.

It might take 2-4 hours for a mechanic in a shop or at a place like speed Inc. But for most of us guys doing it in our garages it'll take anywhere from 6 to 12 hours depending on experience and whether or not you have an extra set of hands. I would suggest setting aside an entire Saturday or Sunday and having a good supply of bandaids, beer and patience.

i got 23 rwhp from my flp long tubes:D no cats
ditto, and I have no cats also.

SLP headers are particularly tricky to install due to the bends. They're about an inch or so wider than most headers, so getting them into place takes a bit more inventiveness.

SLP Long tubes + no cats + loudmouth = sounds like @$$! my set up: SLP longtubes, of road Y, SLP dual dual, electronic cutouts, have not decided whether or not to guy cats, probably will not