i have been wondering this for a while. how does a cat-back exhaust flow any better then swapping out mufflers. for instance say i buy the hooker cat-back it comes with exhaust pipe 1/2 inch bigger then factory and a muffler and tips! right
or say i buy just the hooker muffler.
is the 1/2 inch bigger piping what gives us the persay 10-15 rwhp?

if there is anything ^^^^ there that is wrong please let me know. i am just trying to figure this out.

 

stock y pipe is 2 1/4" and the rest is 2 1/2"....

HERE is a link that shows a dyno test on a borla cat-back....

I have 2 1/2" y pipe and hooker cat-back, and it made a difference....

 

Adding a cut-out will free up a lot of back pressure at the track.

 

also what you have to think about is that the fac. exhaust is kinked at the bend points and the aftermarket systems are not. This alow alot more even flow over fac. So when the pipe is a little bigger and flows alot better than stock, that's where the extra power comes into play.

 

Actually I think the stock system on the V8's is a decent system to start with... Stainless Steel, 2.75 inch, mandrel bent. Good stuff.
Of course there are gains to be had going to a 3 inch mandrel bent system, so it depends on what your priorities are.

Just looking for better sound? Buy a muffler to replace the stock one.
Looking for better performance? Buy a catback.

 

n2ceptor ....are you on crack!!!??? the stock pipes are not 2 1/4...they are 2 3/4 inch, compression bent. the tailpipes are 2 1/4 but not the actual exhuat I-pipe.

edit: sorry you were refering to the Ypipe...but still the rest of the exhaust IS 2 3/4" not 2 1/2"

Lower.....only the LS1 exhausts are stainless mandrel bent 2 3/4". the lt1 exhausts are aluminized (i think) compression bent tubing, 2 3/4" dia.

there is a SIGNIFICANT increase in flow going from 2 3/4" compression bent to a full 3" mandrel bent tube!

and since most exhausts can be installed at home with no welding, why spend $75 on a muffler, and $75 for the welding at a shop, when you can have a full 3" catback for less than $300

 

well teke and lower if what u say is true that is the answer i was looking for. i want the performance and i did not know that there was a considerable difference of airflow going from the two different types of tubing.
just trying to figure out if this catback system is kinda of a scam!!

 

Huh. Pulled mine off of my LT1 a couple of weeks back, and it did NOT have any compression bend marks on the entire system. I sure hope I didn't pull off an aftermarket system and throw it into the garbage!

 

were the exhausts available on the formulas and SS different....more than just the muffler...

that could be the reason for no compression bends. however i think they were still 2 3/4"

someone could probably answer better who knows the specifics of the SS/formula better

on a side note...if you do the math...a 3" tube has 16% more volume than a 2 3/4" tube...regardless of compressionbends or not...that's a nice increase in flow. not to mention added flow from a better muffler

the catback claims are not scams....however i thinkk some of the gains are exagerated a bit. i honestly beleive that the free-est flowing catback being the loudmouth will gaiin you 12-14hp depending on car, and the standard flowing catbacks will gain you 8-10hp. these gains are far from the advertised "up to 30hp gains" that we see all the time. for me it hardly makes it worth spending $600+ on a top end exhaust, but $300 for 10hp and a killer sound...is a bit more acceptable.

 

All V8 F-bodies sold in the US & Canada had 2.75 inch stainless, mandrel bent I-pipes. The only exceptions were the optional systems available on SLP cars.

European F-bodies came with the V6 single outlet exhaust, and were rated with less hp than North American Versions.

By upgrading from a 2.75" to a 3" full catback you gain 1.1 square cubic inches of I pipe cross sectional area. How much that adds to hp, I' ve no clue, but most of the performance gained from a catback is definately in the muffler. If the stock system is capable of supporting 300+rwhp LS1's I think a muffler upgrade is plenty for a bolt on to mildly modded LT1 car. I doubt there would be much if any noticable difference between the two.


In my opinion, if youre on a budget, a muffler will do you just fine.

 

im not on a budget, but i dont want to put the money where it is not needed.
but i do see that everyone here has a catback system so there must be a plus in doing the full catback.
someone should do i dyno with stock muffler, then aftermarket muffler then catback system. that will answer my ? best

 

I just have a muffler.

I'm 90% sure I wil get my car dynoed last week. I'll let you know the results compared to other people on teh board with similar mods and a catback.

 

yo steve u meen next week?

 

Oops, yeah I meant next week. I'm going to call to set up an appointment tomorrow. I'll let you know how it goes.

 

imo, if you plan on keepint your car mostly stock and not doing much modding as in exhaust and you just want some hp and sound from just a muffler than get that. otherwise if u want lt's cat or no cat, get teh catback. u wouulldnt want to have lt's and a y-pipe going in to your stock i pipe and into an aftermarket muffler would you? i would get all aftermarket like the lt's ypipe and catback plus it makes it look a ton nicer. also steve0 is right. the stock exhaust is 2.75" and stainless steel as well as mandrel bent. cant beat that. i liked the stock exhaust i thought it was pretty goo dfor stock.