Old crapy exhaust 6k easy, new exhaust bogs at 4k

So I had a very loud car. Sounded like it had blown header gaskets.
But it turned out to be the exhaust system.

It was pretty much rusty from the “cat” back. [Cat is gone.]
Lots of holes and blow through along the whole pipe. Especially at the bends in the back over the axel.

I don't have very much money so I removed everything bad.
And ran a new pipe from the cat position to just before the axel.
I stuck a $20 AZ muffler.

All the pipe is smooth and straight. And the system is about 3 feet shorter and it has to flow better. But it would easily rev out to 6k before like no problem. It didn’t stop till you lifted. Just hold the pedal down. Now when I give it the gas it will hit a flat spot at 4k and I need to lift and float the pedal some or shift. Like the pedal input is too much.

The stock muffler was a rust piece of crap full of rust too.
I can't see it being a backpressure issue but maybe?

Other idea. I run RP 20/50 oil and it never had a problem with it and good PSI.
Maybe now that it does free flow, the oil is making a difference?

The car is a 2.8 stick shift. It was rebuilt and bored once. But not sure on the spec’s.
But the change happened during the exhaust work. But it seams strange that a shorter all new system would do that.

 

If you let up on the gas a bit and it runs better, that's a pretty sure sign it's running too lean. Hard to improve this on the V6, but need higher fuel pressure, bigger injectors, or maybe a custom chip in the ECM. And it could be something else too?

 

Even if it was lean, I wouldn't change it.
300miles for every 3/4 of a tank is why I keep the car a V6

It may not be fast in V8 terms but I can pass and merge into highway traffic just fine. And I get better mileage then hybrid cars.




It was the muffler though. I yanked it off and it rattled big time. Something inside must of came lose or wasn't installed right.

AZ gladly gave me a new one for my trouble and problem is fix.