What makes me say the limit is 8, because the gains would be more of a percentage of the engines factory power. Since the engine only produced 88 hp when it was new, and I find it unlikey that you will get more than a 10% increase at the most from those mods, the answer is 8 hp. Most folks say something like 10 or 15 because it s a nice round number, and its a guess anyway. But I guess most folks say it, so it makes it a fact by consensus.
Yes, you are right, it increases pressure in all directions, but it won't work its way back to the engine, because the hot exhaust is moving to fast. It will go into the cats, heat up, expand, can't push back to the motor, so it accelerates toward the exit. Because it is now moving faster than it was going in, it also creates a stronger wake behind the pulse. This wake or relative vacuum helps draw out and accelerate the next exhaust pulse that exits the engine.
Induction is the process that defines how any mass of matter moving through a tube, through a fundamental process known as inertia, doesn't want to change its motion. If you blow through a tube, does the motion through that tube really stop the moment you stop blowing? No, it has mass, it wants to keep moving. Forced induction is a process by which this mass is increased and pressurized, the same principles apply. All engines experience induction because both the intake and the exhaust are made of tubes. The efficiency of this induction and the size of all the components defines how much potential power you can produce. This doesn't mean the process is free though, you still have friction to contend with.
A catalyst is a basically acting as part of that induction system, and will accelerate the gases as the pass through it, so long as those gases still have a usable fuel to produce heat with. If there is little or no fuel in the mixture, then the friction of the catalyst will simply slow the flow down, and breaks the induction affect and will produce backpressure.
I would agree, that the catalysts from that time period did leave some things to be desired. They are a little long, that length means more friction, which could exceed their added induction, resulting in a slight power loss, a shorter catalyst would resolve that. The coating technology was not as good, so the efficiency of the reaction was lower, which may interfere as well. And the cell walls were much thicker back then, which would make them more restrictive to flow than a modern catalyst. Then of course, the factory cats, and most aftermarket cats are not really high flow cats.
In the end though, I guess its your car. I just see lots of guys taking of cats, and assuming that because its louder, that they have more power. I'm not going to say its always the case, but I have seen many vehicles, including older '80s vintage vehicles that run worse without them, most often noticed as loss of low end torque and a decrease in fuel economy. The same with modified intakes, sometimes a larger intake helps, but it sometimes kills the low RPM throttle response.
Then of course there is the smell and the safety hazards. I hate driving behind someones stinkmobile. Of course it doesn't bother them, they can't smell their own car. And my brother nearly died from carbon monoxide poisoning, and it came from a car that did have a properly functioning cat. It had a crack in an exhaust manifold, and the small amount that leaked through that was more than enough to cause poisoning. Vehicles that don't have cats produce a lot more.
I would focus on other areas that need improvement first, stock mufflers are terrible, and the stock manifold isn't that great, the later tubular ones are much better. You can improve the intake a lot.
At the end of the day though, the 2.3L does not respond much to simple mods. 16.5 is still slow. Is that quarter mile or a zero to 60 time? Either way, its slow. If you swap in a turbo motor, now you are talking. And on the turbo car, eliminating the cats makes a huge difference. A turbo motor will produce more than double the power your engine does now.
i have been clocked on Daytona speedway at 155 mph
