hello...interesting and more learning....I will say that ONLY Clifford currently makes 1 5/8" headers for truck applications and universal fit short tube headers...If you have seen a set of 1 5/8" headers that were new, they were NOS(new old stock)- I have confirmed this many times with Dynomax,Hooker,Hedman, Pacesetter and Clifford and only Clifford makes 1 5/8" headers at this time....I have seen, touched and measured all 5 of these....from my research I have also found none of these manufacturers make car headers at this time-please correct me if I am wrong about the car headers.....as far as performance is concerned, Long tube headers allow a larger power/torque pwer range than short tube headers...if your your results are different then thanks for sharing, but as a general rule, the shorter the tube the smaller the power band, the longer the tube the longer the powerband...and yes an exhaust system does change all this,so for best street results you can tune your engine torque/power band by your exhaust system-short tube vs long tube primaries,collector length and size,chambered muffler vs straight thru(chambered mufflers are best for low end torque due to flow restiction at mid and upper rpm's and small diameter pipe straight thru mufflers are generally good for BOTH low end/mid torque and upper power-NO flow restriction)...of course we all have different opinions-mine are based on at least 15 different exhaust combo's(header design,primary pipe size,collector pipe size and length,muffler desigh-both chambered,straight thru and glasspacks, length of exhaust sytem, dual or "Y" together, where the dual ends, where the "Y" starts and ends)-what I state here is my experince in having a daily driver Inline 6 for over 20 years-if this helps Great!!!On my current 292 I have had 5 different combo's...one thing to also consider in all this is that there seems to be VERY little info on what sound waves do to engine performance-just as harmonics create problems and rob HP,so do sound waves that cannot flow quickly away from the head/block/crank-harmonic's are vibration waves like exhaust sound waves...the sound waves can only add to harmonic problems of engines if the sound waves cannot move away from the engine and not back to engine-especially the Inline 6 ..this can be confirmed in MANY books written on exhaust and tuning exhaust for HP....also find as many "old school" 6 cylinder engine builders-street,hotrod and racing-they have more info than you can imagine....if the sound waves hurt your ears, what are the sound vibrations doing to the engine???
again its how you build your engine and what goal you have....I will say the 2 most important addition's I have seen on my Inline experience,is when i had my 1st Long tube headers on my stock 250 years ago and then what I consider is the most dramatic change to these Chevy Inline engine's - the Bolt-In Lump.... I will thank those who have have inquired about them and am also surprized by those that send me "not so friendly" email about them ....now if I told you what "old school" engine techniques are in my 292 drag truck that is built and running, some would say "that will never work!!!"..it was good for 9 sec quarters in 2800 lb Nova's 20 years ago with engines that didnt have heads as good as the WAY OUT Bolt-IN Lump head mods I have learned from PES....its so amazing what keeps happening and I feel lucky.....Lets Have FUNNNN!!!!
Lee
[This message has been edited by LeeLites (edited 12-30-2003).]
