WipeOutXXL

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....

jd13

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.

35thanniv.SS

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.

hrtbeat2

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

WipeOutXXL

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.

Black91Z28

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

chpmnsws6

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

tbyrne

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

stik6shift00

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

Black01_Z

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

Aklaim

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

Camaro ChriSS

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.

stik6shift98

i got 23 rwhp from my flp long tubes no cats

chevy qc

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).

in2ta

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.