i'm the 3rd owner of my rx-7. 2nd owner didn't know too much about cars. 1st owner lived in texas i think; there's a rotary performance sticker on the car (garland, tx www.rx7.com). i called them to see if they had records on what was done to my car but they couldn't find any. anyways, when i had my turbo timer installed, i asked the guy doing it to take a look at my car to see if anything looked modded. he said i had a downpipe... "it's too large to be stock", he said... is there any way for me to tell if i do have an aftermarket downpipe? i wouldn't wanna buy another one if i already have one...

 

To check it look under the car and when the piping goes up into the engine, is it just a straight pipe or is it a huge canister? IF its just straight metal pipe thats a down pipe. You can also see it by looking under the hood too. Shouldnt be too hard. If its just a straight pipe its a down pipe, if its not then its a stock pre-cat.

 

By straight pipe I mean nothing but a tube of 3", it will be mandrel bend so dont take me the wrong way.

 

The downpipe looks like a pipe with a bulge in the middle - like an anaconda that just ate a pig. If it is completely stock, there'll probably still be some heat shields surrounding the pre-cat.

Best way to tell is to look from underneath the car, locate the exhaust pipe, and follow this back to the engine. If the diameter of the pipe remains relatively constant (although an HKS downpipe will not be round the whole way), you've got a dp. If you see a bulge near where the pipe attaches to the engine (not where it attaches to the maincat side), you've got a pre-cat.

Also, if you need a better idea, go look at the service manuals online and you'll find a good pic of the stock dp and where it attaches to the engine.

M

 

Precat has the silver colored heat shield surrounding the entire pipe.

DP will be just the pipe without the heat shield.

Best place to see is from behind the front passenger side wheel. It's easy to see the pipe.

 

thanx guys ... checked today, i it looks the way you guys described. no heat shield, 1 mandrel bend... looks a little old tho ~shrugs~ probably not stainless steel.

 

yeah, even SS will turn color with the high temp exhaust. Some said theirs are still shiny bc I think most start to turn brown with age.

 

The original one is huge and weights almost 50 pounds. As for an aftermarket you can hold it with one hand. It is a strait pipe with a stub for the O2 sensor. The oringinal should be very dirty and stained with grime.

 

According to my bathroom scale, Precat weighs 20 lbs, most DP weigh 7-10 lbs depending on SS or MS. MS are a little thicker and therefore heavier.