Ok just a few questions for you guys. 1 - i have never heard of an OBD1, does a 95 z28 have OBD1 or OBD2. 2 - Generally all aftermarket headers are going to be better than stock manifolds, but i was wondering what the difference is between Long Tubes ands shorties, obviously one is shorter than the other but why ? I here short give more tork and Longtubes are better for HP but thats could be B.S.! Finally when im going to install my new headers, im going to need a new Y pipe, do most companys who make aftermarket headers for my car also make a aftermarket Y pipe, becuase i dont much feel like having one custom made. I wanted hooker Long tubes but i hear they have terrible ground clearence. So what are some really good headers with decent ground clearance, that are pretty loud and give a decent power increase. Finally if i want to gut my cat (sorry i know this topic has ben run into the ground) will i need any type of new O2 sims for my 95 Camaro z28 6speed. I heard it releives allot of backpressure when you gut the cats and the front 02 sensors sence a change making the cars performance drop. Well tell me what you guys think, thanks for reading!

 

A 1995 car has an OBD 1 computer with an OBD 2 style connector. A lot of people like Longtube headers because they create excellent horsepower but some people need shorties because of emissions. You will need a custom Y pipe made for hooker longtubes unless you want to pay $250 for a Mufflex Y pipe. annnnd You dont need o2 simms because you have an obd1 vehicle.

 

Anything earlier than 1996 in an F-Body is "OBD-I". There never was an official EPA defined set of requirements for OBD-I.... it was sort of up to each manufacturer as to what they included. OBD-II is a defined diagnostic system, with a certain degree of uniformity accross all manufacturers.

It is a generalization that the longer the tubes, the lower in the rpm band it moves the scavenging efficiency, increasing torque. But there are so many things that come into play, its almost dangerous to generalize. Depends to some extent on how the engine will be used.... a street engine wants low RPM torque.... a track only engine that spends little time under 5,000rpm may want improved high RPM scavenging. I think its safe to say that a lot of people have had very good results with the Hooker LT's, but I have seen dyno tests on a strictly race application, where the LT's couldn't match a set of AS&M mid-lenght headers, until the engine reached more than 900 flywheel HP. I personally don't think you could go wrong with the LT's, and not be too far off the mark with the AS&M's if you can't fit the LT's.


Almost all the single-cat shorty and mid-length headers I have ever seen for the 4th Gen's come with a Y-pipe. The Hooker LT's do not, and require one from Mufflex, or custom made. The FLP LT's come with a Y-pipe, cats, and off-road pipes.

Personally, "sound" would be my least important criteria for headers.... get the ones that produce the most power, then play with the rest of the exhaust for sound. I personally like either the Hooker LT's or the AS&M mid-length.

Your OBD-I 95 will not need O2 sims, there are no after-cat O2 sensors on the car. You can not remove the pre-cat O2 sensors... they are needed by the PCM to control A/F ratio at part load. You could remove them, but then you would have to have your PCM reprogrammed to operat in open loop at all times... not really a good idea, since it may increase fuel consumption, plug fouling, etc. And if you have any emissions at all to worry about, you will need some outstanding tuning.

I think the "lost power due to less back-pressure" is all myth, left over from the days of carb motors. Modern EFI setups can adjust mixture to maintain performance. Anything that makes your exhaust flow better will gain power. I have also seen high flow cats that have next to zero impact on power, so to me its a good idea to run cats on the street, and remove them at the track.... just my personal preference.