When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Whether to remove the cats or replace them with hi-flow cats is a matter of personal choice. Some have kept cats because of their concern for the environment. Others have noted a bad smelling exhaust after deleting cats. I chose to remove my cats - they weigh a metric sh*t ton - and I haven't experienced a bad smelling exhaust.
If you can get your car high enough on jackstands (i.e. Ed or I could slide under it ). You can probably do the X-Pipe and cat removal/replacement/pipe substitution yourself. You will have to fit four clamps, but that shouldn't be too hard.
The worst part of any exhaust is getting the old stuff off. I had no trouble in that regard when I did mine.
Figure out how much you want to change. If you are going to redo the whole shebang AND all the stuff you need to take off is rusted solid, then take it to somebody.
Thanks all for the information! You all are awesome!
The reason for keeping the Cats is not for the environment or smell, but more for if I ever have to sell. (I hope not until I croak ) Does that make sense?
Going to lift this weekend and take a look. I would most likely take it somewhere with instructions on what I want done and have the parts already.
What I'm thinking I want is, add the X pipe, keep the Cats, resonator and muffler. This is still in the deciding stage though and won't be done until spring.
OK Rick. Here is a picture of a mostly stock setup for your 85.
The only portion of that pc that is not stock is the rear muffler bypass.
I think of the exhaust in four sections. Each of those sections serves different purposes and has different options.
1. Manifolds or Headers (attached to the block)
The manifolds pictured in the center are from a 79. The ones on your 85 are much lighter and each individual pipe is more similar in length.
2. Catalytic converter or X- pipe or H- pipe(test pipe)
The one on the left is stock to the 85, the one on the right is by Louis Ott via Dave Lomas. (or so I have been told)
3. Mid muffler/resonator/ or straight pipe
4. Rear muffler vs rear muffler bypass
Lots of options and lots of opinions as to which is best (whatever that means).
Some sites claim a 30-40 hp gain with the x pipe alone (I hope they are true)
Some folks say the RMB is worth 20 horses.
Do what is right for you and your budget and do not be afraid to make a mistake. You may pick a combination because it makes sense on paper but then end up hating the way it sounds. No biggie, you can change it.
Car parts are like guns and gold......., eventually you can get your money back.
BTW: my 79 has a Borla mid muffler and a Borla rear muffler. It sounds great. The system from the 85 sounded kind of mean though. I miss that low rumble.
Rick,
Given what I know of your car-
Well even with that it depends on how deeply you want to get into it and tolerance for slightly too loud under some conditions in order to have a nice tone at others. I've been through several combinations on several cars- I agree that 16V sound better- when properly subdued or else fully wound out.
32V I've found tough to get an assertive idle without some annoyance mid range on the street.
You might consider picking up a used 86.5 cat back, which lets you switch between a few options. A lot of folks like the separate mid mufflers with an RMB, either prefab or made.
The x pipe is nice though, in that it should provide some increase in HP as well and with hi flow/low cell count cats will retain low end torque and a good balance of sound control.
Back with my 85 years ago, I first had a custom straight through dual in/out muffler fabricated to replace the factory center...very little change. Then walloped off the rear muffler. That was silly. Then put some cylindrical chambered resonators where the rear pumpkin was...still too loud in upper mid range but drove it that way for a while.
I've read and re-read exhaust threads. I also have just purchased an 85' s and from General consensus an X pipe is the best bet without having to have an exhaust made for an 85. Yes?? And who offers the best and who offers the cheapest? Also if I wanted a RMB is it a cut and fab job or is there some already made ones. And the last. I live in OK so there is no emissions tests.. I want the cats gone. Do I have to do something special with the O2 or the fuel ratio or is it so minute that it doesn't matter. Please and thanks!
Does the '85 have a true dual exhaust? I thought I had read that came in with the '86.5. At any rate, I think all the major vendors have x-pipes for the stock manifolds, with or without cats. I needed one for the MSDS headers, and Carl has those at 928Motorsports. Or, he did. I may have got the last of those, pending a redesign.
Dump the cats and replace with an x-pipe. Keep the cats in the garage and sell them with the car. Old cats can loose you a fair amount of hp. My S4 has cats removed and a silenced RMB. Not too loud but sounds awesome when idle or giving it full throttle
Mine has a port for the o2 sensor so was a straight swap. I was celebrating good results on my flex plate release /check and had dropped the exhaust for access and was just looking for a bolt on replacement. You can probably get something cheaper. I'm uk based so the vendor may be no use to you but I got mine from here.
This is a DIY job you can definitely do on jackstands. Plan on cutting/drilling off the original bolts but then the new one will come with all of the hardware you need.
If you keep the stock cats you currently have you can offer them with it if you sell.
This pic shows optional hi-flow cats which I would recommend. Then when you sell it you can show that it would pass inspection as-is, or they can replace with original. Also, just because the law says you can go without, do you need to? They don't restrict any appreciable amount and your great grandkids will thank you. alternately they come with a set of straight-pipe sections that you could put in their place between the crossovers and the rear exhaust. I have mine sitting on the shelf and you're welcome to them. I'll never use them.
Call Roger at 928sRus or Carl at 928 Motorsports.
It is completely bolt-on, will sound awesome and will add HP that you will feel.
Additionally, if you have a 5-speed you'll have access to the clutch without removing your exhaust. Which is a MAJOR PLUS.
12-12-2014, 03:00 PM
). You can probably do the X-Pipe and cat removal/replacement/pipe substitution yourself. You will have to fit four clamps, but that shouldn't be too hard.
) Does that make sense?
alternately they come with a set of straight-pipe sections that you could put in their place between the crossovers and the rear exhaust. I have mine sitting on the shelf and you're welcome to them. I'll never use them. 
