one03sierra

iTrader: (1)

wow. well i removed my cats since i was going to go to nitrous. a 150 shot. and i am running a 216-220 cam as well. when i went to the track i ran 2 tenths faster with the exhaust a true dual and a single magnaflow. damn-385.00 for all the work and that was it. then i hit the juice and wow--12.85.now i like the fact i can run race fuel and have the gains i have. and a stall is a big help as well. maybe i got lucky and my set up just happened to work. i agree with big tex on the cam thing.

oxidizr

iTrader: (4)

As a development engineer for exhasut systems I can say that OEM's are sourcing much better exhaust companies when it comes to who makes their exhaust components but to be honest their really isnt very many different engineers doing the work. Did you know the same company (Arvin) makes the mufflers on your GM as does makes the mufflers on the BMW E46 M3? Well... its true.

It is a fact that exhaust systems are very much an after-thought, they do sacrifice much to do what they are designed to do ... make things quiet and expel waste gas effectively... not most effieicently. There are degrees to this which differ by application of course. If you driving and economy car your are getting an economy exhaust. If you are driving a truck you are getting an system designed to provide good throttle response and noise control under load and if oyu are drivng a sports car you are getting a more tuned exhuast BUT remember the SAE and J1169 compliance (tailpipe noise level) for all motor vehicle is the same so you are going to loose something to noise attenuation.

Having driven 100's of cars on dynos before and after exhaust work I DO have a good experimental background and having designed many of these on paper / CAD and with the aid of a flow bench can say that all the general rules of "backpressure," flow velocity and pretty much all basic principles of fluid dynamics apply BUT the uncommon variable here is the air pump ... your motor ... configurations of headers,firing order, cam profiles, and compression all play a role in making a "tuned" exhaust.

When it comes to the whole "open header" at the track vs street performance you must look at defining the role of the exhaust system. Are you in fact building a race only system or a well tuned street system. I can attest to open header being optimal for track conditions but honestly I have PI vigilante 3500 converter mated to 4:10 gears and run on the bottle ... how many seconds at the 1320 do really spend under 3500 rpm??? 0.750 seconds? If in fact i spend this little time at this rpm range why would i tune for it? I need to remainder 11.5 secs of the pass which remain above 4200 rpm. On the street throttle response is what makes your vehicle drivable and pleasant to drive, not to mention easier on the wallet when it comes to fuel (trust me my lead foot and my setup net me 9-10 mpg averages!) So having a exhaust system that promotes good throttle reponse and makes more available 0-3500 rpm torque is what is optimal for street ... if you are trying to have the best of both worlds it is going to be very difficult as compromises must be made in one arena or the other.

All in all its not astrophysics ... just address your real needs ... do you want to have BIG just because its BIG, do you want to have an all out RACE performer or one with good street manners too or are you after looks and sound. The exhaust after market is quite large and really there are options to meet all these needs and even some that do a half way descent job at addressing most but really few meet all.

Richard

one03sierra

iTrader: (1)

and i think that is why i want to put cats back on here. but i love the fact i have top end with my exhaust now. but i do more cruising and tripps in it than i will race.

tooquick2beslo

I would have to say that dual exhuast beneftied me. I gained 1 tenth and 1 mph just by making my own true dual exhuast. I didnt literally make it i just told the guy at the muffler shop what I wanted done. I have true duals with 2 flowmasters. I just recently cut the tail pipes off and it sounds way better now.

bodyguard6799

For right now my truck is bone stock and when I get my headers (Thorley ceramic Tri-y's) I am going to rework my exhaust keeping the cats. I am not drag racing its going to be a daily driver but I want the best gaine possible and I love the way turn downs sound. I do plan on some other mods intake, pulleys, e-fans, free mods, custom tune. Nothing major because I dont have the cash for it right now. I dont want to have to change a cam just because I put a free flowing exhaust system on. So would it be benificial for me to have the muffler shop build a true dual setup w/cats and w/out the Y-pipe?? And should I put 2 smaller magnaflows or one bigger one?? What size pipe should I use??