New exhaust yes or no.

There is plenty that can be done with exhaust and intakes on EFI modern engines. Look at the Ford MOD Motors and LSX motors. My own 11 Sec 1/4 LS1 Trans Am is a good example. The difference between an LS6 intake on an LS1 is about 15 to 20 HP at the wheels without a tune.
Next you do the tune and get even more gains. The best way to do it is on the Dyno.

Now having said that a catback alone won't do it. You may see a few hp at the wheels, but you won't even notice it and you will be out at least 500 bucks.

A complete exhuast system with a tune on a modern EFI vehicle may net anywhere from 20 to 40 RWHP depending on the engine and type of exhaust system.

My WS6 gained 26 HP and 32 FT/LBS of toruqe from a custom exhaust, stock cats and mid length headers. Then with the LS6 intake I picked up another 16 hp and 13 ft/lbs of torque. All at the wheels, Dyno proven.

Problem is you have to be willing to do the whole thing. Headers, Cats, exhuast and tune. So you are looking at a pretty good chunk of money. 1200 bucks for nice headers, 300 bucks for a dyno tune and at least 600 for a complete custom exhaust. More if you get an off the shelf catback.

If you are not trying to pick up tenths in the 1/4 mile, I am not sure it is really worth it unless you like the sound.

It is why my 6.0 Chevy truck, which is really similar to the 5.7 in my WS6 is bone stock minus a tune to change the Transmission shift points and when the torque converter locks up.

save your money been there done that. i used to have a shop. not worth what little you do get. its all in how you drive and how well the truck has been taken care of.......................

IMO, No!

As far as the cool sound, I had to take out a cold air intake as it drove me crazy. I have been in trucks with cat back systems that had the dreaded droan and others that faded to close to stock as Carrera man says. It seems that you all have the same recommendation. Save my money.

I did it on my 04 F150. I did long tube headers, hi flow cats, tru-X and maggie mufflers. Sounds fantastic, didn't really notice any performance gains. I then got custom tunes ... and that I did notice. Feels like a whole new truck. Can't believe the performance improvements out of $500.

Well we just completed ours on a 6.0 07 Chevy crew cab. A few weeks ago we installed Banks headers since we had a broken exhaust stud I saw no reason to reinstall the cast iron manifolds. We then towed our enclosed trailer and picked up about 1 mile a gallon or so. Performance wise, it felt slightly better, maybe a few HP. I knew the headers could only do so much with the stock exhaust system and unlike the comments above the stock cat back exhaust was fairly restrictive on my truck. So yesterday we installed a cat back Gibson single exhaust. Although we haven't towed with it the motor has come alive and revs much free'er then it had. Almost feels like and overhead cam motor now. It is a little noisy in the 1200-2300 rpm when accelerating, once at cruising speed it sounded close to stock. I've raced enough of street cars to know that the best way to increase HP is to dump the stock exhaust. Even when I tracked Porsche's the exhaust was the first place to gain HP, and they have very good exhaust systems from the factory, far better then what was on my truck. We'll see how this translates into MPG when towing my trailer and if it was worth the $$ or not.

That "cool sound" causes many to complain about the "drone" on the highway. It wouldn't be what I would spend my money on. Even my cool sounding Harley is starting to aggravate me. I must be getting old.:(

You will see essentially zero true performance increase. All it will do is sound louder. Mind you if you need an exhaust anyway, if you want a loud one, get a loud one. Gas engines these days are just not open to performance gains from playing with intake and exhaust, you're as likely to lose as gain in real life usage and conditions.

Brian

Supercharged wrote:
I had one on a 2003, didn't see any reason to spend the money.

I'll take that as a no.

scootsk wrote:
I have a 2002 Silverado crew cab dually with an 8.1 liter. Thinking about upgrading to a performance exhaust. Is it worth the money to do a cat back on this truck. Are the gains noticeable while towing? I know they sound cool but I want performance increase.

I had one on a 2003, didn't see any reason to spend the money.