RKD in OKC

Got my cats with the x-pipe from Roger. Sean and Roger fixed my clutch at a 1st Saturday tech session. While fixing the clutch arm ball cup they forced me to drink lots of beers and refused to put the stock cats back on so my only option was to go with the x-pipe Roger had conveniently brought to the session. I sprung the extra bucks for the sport cats because of the exhaust experience I had with my 90GT. Oklahoma doesn't have emissions, I did the cats specifically for the sound.

When I bought my 90GT from Jarrod it already had the RMB and sounded fantastic. In my quest for power I gutted the stock cats. With the gutted cats and RMB I got 15hp but it sounded like Saturday nite at the fairgrounds oval, way too loud. Adding back the rear muffler only cost me 3 hp, same dirt track sound but it toned it down to soundly like a couple of miles from the fairgrounds. Even though I liked the stock cats and RMB sound a lot better I just couldn't bring myself to give up the extra power. There was no x-pipes available when I did all this to the 90GT. Before I sold the 90GT I was planning on headers and exhaust from Louie Ott. In fact, I had already gotten his UniChip. When I sold the car it dynoed 315rwhp.

coast928

Just summarizing some points others have made here. I think we can all agree that Autothority chips or their cheap eBay clones are old news and the way to go nowadays for pre-'87 cars are with Porken chips and an '87 FPR or for the ultimate solution, burn custom chips with a Shark Tuner from JDSPorsche.
The X-pipe has always been shown to be a good solution to obtain some hp. But those concerned about emissions will have to go with aftermarket cats when using the X-pipe since the stock cats can not be used with this application. Though some have commented in older threads that the aftermarket cats don't last as long (maybe 5-7 years at most) compared to the stock cats. (Maybe with newer catalytic converter technology things have changed now? Haven't heard yet.)
RMB's (rear muffler bypass) have been debated, some like them, others think they are just too loud when combined with the X-pipe and offer only a few hp at best, maybe none at all that's noticeable on the street. Most put them on for the sound and/or the weight savings compared with the stock rear muffler. Hope I got this right.

RKD in OKC

I seem to remember from long ago that RMB vs Stock muffler was 3 hp.

GlennD

Greetings,

Thought I would weigh in as well.

I have an 86.5 with Ken's chips. I purchased a used catalytic converter from 928 International and had the catalytic converters cut out and replaced with very low restriction resonators. This stock Y piping has a build in X-over where the O2 sensor goes. Works well - no issues bolting on, no issues with alignment of the O2 sensor, and no issues with connecting to the downstream exhaust piping.

My final set-up is this piping arrangement above (two resonators replacing the two catalytic converters), the two stock 86.5 resonators, and a RMB. It sounds great at heavy throttle, highway cruising noise is very acceptable (cannot really hear it with windows and sunroof closed), and has a good throaty idle.

I am toying with putting the stock pumpkin back on just to hear the difference in tone.

For information, I purchased the used factory Y pipe with used catalytic converters from 928 International during their 50% off used parts (just before Christmas) for $150 (plus shipping). The cost of cutting out the two catalytic converters and replacing with resonators was $220. And, I still have my stock set-up ready to bolt in should I need (selling the car, etc.).

The O2 pump was disconnected and the outlet (where it connected to the stock cats) was plugged off (covered) so future reconnection is simple.

Just offering as an option to the X-pipe arrangement. I am happy with it

Cheers
Glenn

Franks928s

James-Man,

I live in Charlotte and would love to hear what yours sounds like. I have both MY85 and MY87 and thinking about exhaust mods.

Frank

Richter12x2

I have a x-pipe with Porken's chips, and it seems fine to me. A touch on the loud side, but only when I press the pedal down, at cruise it seems fine to me. Plus, it was an awesome feeling when a newer BMW revved his engine at me at the redlight one day, and I revved back and every car around me moved away a little bit.

dcrasta

I want my 86.5 to sound just like that

James-man

Frank - I am in South Charlotte. I'd be happy to be of assistance.

Bill Ball

I'm reporting back that I swapped out my 89 resonator sections of the exhaust for 87 sections, which have MUCH larger resonators. Now the exhaust sound with x-pipe, no cats and RMB is actually rather quiet. PERFECT. I can drive ther car without setting off all the local car alarms.

Iwanna928

I recently removed my cat. I was thinking about a x-pipe. Would there be a benefit or gain on a 16v like there is on the 32v?

bcdavis

My answer to raspyness on many different exhaust systems, on several different cars has been the same:

http://www.eraceware.com/pacesetter-...al-112288.html



Try adding one of these with your x-pipe, instead of an RMB, and instead of your stock muffler...

tveltman

On my '88, I was very pleased with the x-pipe, high flow cats, stock resonators, and RMB. It wasn't too loud, but it sounded good. I plan to delete the resonators with a custom cat-back, so we will see how that goes.

edi1

hi
have headers x pipes no cats .stock muffler. sounds good

Louie928

For each combination of different exhausts, intakes, cam timing, Sharktuning will give the best result.

A couple years ago I worked with Ken (porken) on enhancing the performance of his '85 or '86 (can't remember which year it was). Ken had stock chips and aftermarket chips which I think were clones of Autothority.
We tried many combinations and sharktuning. One of the first revelations was just how bad the aftermarket chips were. The fueling was all over the place with the top end way too rich. I don't remember what improvement, if any, the timing was with the chip. Overall, the chips weren't worth the box they came in. The stock chips were really pretty good on fuel and a lot of gain could be made with timing changes. I think we ended up with close to 300 rwhp and that was on an auto trans. Ken went on to further develop his chips along with optimising the temp sensor effects. Ken had some exhaust changes too, but I don't think it was a "standard" X pipe. Check Ken's web site to get the whole story. I may still have some of the dyno runs around. These early 32v cars have a lot of potential to offer.

Bill Ball

The 87 resonators tame the the X-pipe + RMB caucophony very well. It still sounds like you mean business but much more subtly. My car was more annoying than a ricer with a 5" coffee can muffler before I swapped in the 87 resonators. Deleting the resonators without some muffling would be unliveable unless the aftermarket cats do some.