Andy13186

This jegs catback, (Heartthrob also claims the same HP gains) claims to give 21.7 hp

http://www.jegs.com/i/JEGS-Performan...31151/10002/-1


Is this true? Can anyone confirm that this with an axleback would free up 21.7 hp without tuning or anything?

do catbacks actually free up a decent amount of HP like these people are claiming? The dyno sheet just looks wierd on heartthrobs website

http://www.heartthrobexhaust.com/1029050dyno.pdf

They also only rev it to 6400 rpm? that dyno sheet just makes no sense..

heres heartthrobs video

http://youtu.be/_MGRvx5RRDw

Looks like they run the 1st dyno run in like 2nd gear possibly or is that an automatic in 3rd? Seems like a pretty short dyno pull.

At 7.23 he says they gained 12 hp from the axleback system.

at 10.20 he says 22 hp gain with catback piping with h pipe.. i belive the cats and 02 sensors are infront of all the pipes they replaced.

at 10.38 he said the same setup but with x pipe freed up only 6 hp

any thoughts? Anyone have a catback and dyno results?

Mishri

Without even looking I can say nope, no way. No reputable tuner I am aware of has ever seen any gains from an axle-back exhaust on these cars. Not any gains that aren't within the normal margin of error on a drum style dyno.

edit: i read jegs' report, 8.5hp from the axleback section that looks like a straight through muffler delete and no tips. and 21hp (I'm guessing they are guessing BHP) from the o/r mid pipe. The pipes all look poorly made and ultra cheap. If you read it says that it deletes the cats on the mid-pipe. 21bhp from a header back system? sounds like stretching it a bit but possible. but the axle back im thinking they are estimating way too high. you might see a few hp gain, not worth worrying about.

that PDF you linked to doesn't look like any dyno chart i've ever seen. It looks made up.

i watched the video, he just says they are done dynoing, no dyno shown, usually people show the actual run.. i wonder what they are using? I'm going to guess a computer program that guesses at whp/whtq based on weight and acceleration and gear ratio and tire size from that dyno sheet. which nobody would consider anywhere near accurate.

as far as X vs H generally people say they are about the same, only difference is tone. on the 4.6L 3 valve the H-pipe sounded better, on the 5.0 X sounds better, to most people Their X pipe looks narrower than what I have, much more narrow, perhaps that is their issue, or it's how the formed it, or it's their goofy/innacurate computer dyno.

Overall a cat-back style exhaust system is considered for sound only purposes, you wont gain enough hp to see a difference in the 1/4 mile, which people say takes 10whp to drop .1. an off-road (cat-delete) mid-pipe is going to give you a noticable (15ish) gain. and LT headers will get you a noticeable (15ish) gain. TO me the cost of the LT header's isn't worth the gains, o/r mid pipe is enough.

Andy13186

On these cars it looks to me that the stock H pipe doesnt have the cats.. so i dont know why they say it "deletes the cats on the midpipe" there were none on the stock midpipe.. the cats are just infront of it and look to be attached to back of the headers. Do you really need to go with headers to go catless on these cars?



stock h pipe is catless and removable without the cats being taken with it, from what i understand.

The midpipe is 2.75 inches and cinches down to 2.5 and even 2.25 in some areas according to heartthrob

so catback = header back on these cars?

Mishri

nope, you detach that pipe, where you see those cats, from the headers (the bolts are facing the engine bay).

cat back is not header back, any real midpipe attaches to the header. those cats aren't part of the headers.

this is what my x-pipe looks like



those flanges at the top are where it bolts to the headers. it's a waste of time and money to not delete the cats, unless you think the sound is worth it. In which case you might as well get different axleback exhaust since that controls most of the sound. these cars have factory shorty headers and LT headers dont add a whole lot more power. Only way i'd spend the money on a LT header setup is if I wanted a record bolt-on only car... but my track is at 4,000' so i wont be breaking any records.

Andy13186

Thanks for the info.

Jegs and heartthrob do still claim the 22 hp gain from the cat back replacement 3 inch piping, but i agree that that dyno chart looks fake or messed up.. and they dont even rev to 7k rpm.

I dont really want to delete my cats so if this power is actually possible i would love to do this. The pipes do look cheap and like the welds would rust, I have high temp exhaust paint i would spray on all the welds before installing though, should hold up fine that way i would think.

Anyone else have any thoughts or experience?

Edit, heres a jegs stainless steel version, looks a bit higher quality but 100$ more expensive too http://www.jegs.com/i/JEGS-Performan...31161/10002/-1

Mishri

I decided to look up the dynapack they apparently used..

"The Dynapack dynamometer is a new and surprisingly compact machine designed to apply computer controlled loads to the wheel hubs. It has superior advantages over the established single and dual-roller chassis dynos. The Dynapack computer can maintain a set RPM!"

it attaches to the wheel hubs and applies load. I'm not too sure how accurate it is, especially when I see in that pdf the guy has flywheel horsepower selected (which you can't measure from anywhere but the engine due to drivetrain loss) so bleh, I just don't think much of it.

My final piece of advice is to order from one of the forum sponsors, they have been around awhile, they test most of the products they carry and they have good customer service. If one of the forum vendors sells those then ask them what they think of the product. I don't trust manufacturers to be honest about their products. You could say the same about a vendor trying to sell you the one they have the biggest mark up on, but that hasn't been our experience with the forum vendors. Lethal performance or Brenspeed are usually top choices.

Andy13186

Found a 2012 dyno with just a cat back no tune

http://youtu.be/PoM5DgDwoSc

371 rwhp which is about 426 engine hp not bad, hes using an x pipe too

99gtstang

Odd video - Many would focus on the dyno with live on screen shots. Magnaflow claims 19 RWHP with their O/R X and catback system.

http://www.americanmuscle.com/magnaf...ck-2011gt.html

I too am wondering about getting a Catback vs. axlebacks.... How much HP are the factory resonators robbing if any? Instead of buying a catback, can we delete the factory resonators and straight pipe it in the one spot? How much is the 3" pipe really helping?

SSKILLER5.0

Think 21 hp sounds to high. I'm in the camp that it does increase hp but more in the 10-12 range. Match it with an x-pipe which you can find fairly inexpensive and you will find some gains. It makes it sound like a wicked bitch too!! Thats the best part..If you are going cat-backs just go ahead hop on the breenspeed site and buy the bbk x-pipe that keeps the cats(in case you have smog or inspection issues) and do it at the same time. Pipe is only 189 bucks i think. Its a direct factory bolt on. I put my catback system in myself but I couldn't remove the top brackets on the factory H..had to take it to a shop pretty cheap.

Mishri

people have dyno'd at 365-375whp stock. looks like a regular stock dyno result to me. you can't guess at fly wheel horsepower with these cars, they probably only have about 10% drivetrain loss. There is very little drivetrain loss compared to older cars, or even the 05-10 mustangs. electric fuel pumps and steering. that's why they don't make Under-drive pulleys for these cars.

here is one with a tune and cat-back, 403whp:

http://www.youtube.com/watch?v=TwHos830Y_Y


ive seen 395-400whp tune only. so he may have picked up 5-10 with the kooks cat-back system. kooks does make good exhaust. I've seen a lot of people with just a cai+tune put down 405whp too though.

okay so for a full cat-back system you might gain 5-10whp, from a good system. most people doing an off-road mid-pipe see a 15whp gain, and doing axle-backs see no gain. maybe the engine will put out an extra few hp, but it isn't anything you can measure at a dragstrip. if it doesn't drop a tenth off your 1/4 ET, the mod isn't a performance mod. I've never heard of someone dropping .1 from a cat-back system (requires 10whp to drop a tenth on average) but maybe it's possible.

you can see truckguy's post here:

http://www.svtperformance.com/forums...k-times-4.html

he has a cat-back system, bunch of suspension, MT drag radials, runs 12.0@113. That is close to what most people run with tune+drag radials only, with that trap he is running about as good as it gets. that is what many tune-only traps see. and that is a good way to measure overall power output of a vehicle, about the same as a tune only car.

here you can see steeda ran 11.9@115 cai+tune only.

http://www.youtube.com/watch?v=xFf2EWQ3wTE

this guy ran 12.2@112mph tune-only

http://www.modularfords.com/f259/bbr...hs-off-169510/

it's hard to find many cat-back+tune only times but it looks like from my research the cai+tune is better, and most people only gain about 10-15whp out of the cai. leaving me to believe the cat-back does next to nothing for power.