84-Z28-Canada

Hi Guys, looking for opinions of people who have installed their own exhaust. I have built a 350 for my car (84 z28, 305 currently) and I have purchased: Hedman Shorties (2.5"), Matching Hedman Y-pipe (2.5") and the American Thunder Flowmaster Cat-Back (3", Mandrel Bent).

1)What are the difficulties of installing all of these at home?
2)Should I install exhaust before the motor swap or after?
3)Unexpected problems with parts or fitment?

Thanks a lot guys
Ian

five7kid

iTrader: (14)

1) The hardest part is removing the old exhaust.

2) During.

3) The Hedman Y-pipe is too small. Consider a different set of headers. The Hooker 2055HKR are the much better choice.

You didn't mention a cat. How did you plan on connecting the Y-pipe outlet to the cat-back inlet?

84-Z28-Canada

thanks very much for getting back to me, all of your comments are very helpful. I am considering a cat for the system. It seems that a 3" magnaflow universal with flanges on it would work. In what way is the y-pipe too small? Meaning that it will be restrictive or that it actually won't install properly? You are right about the headers, but these headers came for the low low price of being free, off a friends 85, so it's hard to argue with that. Also, you're absolutely right about doing the exhaust swap at the same time as the motor swap.....I'm just so impatient lol.

five7kid

iTrader: (14)

Unless you're doing the work yourself and have access to free materials and welding equipment, a direct-fit cat is cheaper. But, see below...

Both. It is restrictive because it is too small. It won't install properly with direct-fit parts.

If you cut off the 2.5" portion of the "Y" and replace it with 3", you can get proper flow, and fabricate the flanges & pipes necessary to install a universal 3" cat into the system and mate it to the cat-back.

Need to be careful about "free". To continue with the thought from above, you can spend more at a shop getting things modified and welded up than it would cost to buy direct-fit parts that you can bolt in yourself. It's been awhile since I've gotten out of an exhaust shop for less than $200, even for fairly simple work.

If there is going to be a significant amount of time before the engine swap takes place, then go ahead and install the exhaust now. It would just be easier to do it at the same time the engine is out.

84-Z28-Canada

wow, lots of good information. The headers are a direct fit for this car, but that doesn't necessarily mean that it should be easy to do. The y-pipe is Hedman's suggestion for these headers, and therefore for this car...So I had hoped for a bolt-on kind of set-up at least insofar as the y-pipe was concerned. Now, I knew that the headers and y-pipe had a smaller diameter (2.5") than the cat-back, but I didn't think that would matter. Would I have been wiser to get a 2.5" cat-back? Now, when you suggest switching the 2.5" portion of the y-pipe to 3"...correct me if I'm wrong, but isn't the entire y-pipe 2.5"? I think I will have to take a closer look at the pipe work and see what needs to be done. Also, good point about trying to make something fit instead of buying something that fits. If I can get a direct bolt on Cat that will mate with both my y-pipe and my cat-back...I'd much prefer that (especially because...and again I could be wrong...then I could do it all at home, in theory??) Thanks a million for the replies 57, Going to have to buy you a beer by parcel or something

Ron U.S.M.C.

From what I have found in my search at Summit Racing Magnaflow only offers a cat for your set up in either a 2.25in. inlet with a 2.5in. out let or a 3in. inlet with a 3in outlet. I would go with the 3in. in and out Magnaflow cat using a adapter on the "Y" pipe to the cat.When it comes to cats the Magnaflow is the one I recommend.By the way some of the Flowmaster American Thunder cat backs can come with ether a 2.5in. or 3in. inlet on a 3in. intermediate pipe. Be sure to measure,and last but not least I suggest a complete welding.

84-Z28-Canada

thanks very much for the insight. I will have to double check the inlet on the cat-back, so far as know its 3" all the way. I priced out cats last night, and the direct fitment cat is over $300 where I get my parts from (oi...) however, a 3" Magnaflow Universal is only $100, and the boys at the exhaust shop will weld flanges on it for me for $30. So, that seems to be the way myself and my wallet are thinking. Interesting that you suggested a complete weld set-up. Everything that I've got thus far (headers, y-pipe, cat-back) are designed to be bolt together. If I had the flanges welded onto the converter, it would also bolt up. So then, is it much more of an advantage to get the whole system welded together? and if that's the case, how far would you go? For example, after I put in the new motor, I can bolt up the headers myself...but should I go so far as putting in the y-pipe? and then let them take it from there? First time with installing aftermarket exhaust...so it's all very new and interesting. Thanks guys