I have a custom straight piped exhaust, on a 1.8L tiburon, i cant seem to get the backpressure ratio right. anybody know the specs on the right amount of back pressure the engine needs to be at its peak???

 

All you need is 1 cat and you should be fine with the backpressure. I don't think you even need a muffler (you can use exhaust tips) as long as you have the cat.

 

Im not sure of the ratio? But unless you run a muffler, your not gonna get the correct back pressure for BOTTOM end.. Not even w/ a cat will you have enough.. If you want straight pipes and have the luxury of bottom end w/ backpressure, install a wastegate before the muffler (electronic is nice)..

 

You can ask Random at HA, He ran a cat with no muffler for a while-he only used exhaust tips at that time-so he said.

 

How many inches are your straigh exhaust pipe??

 

I have a 2.0L and am running 4-2-1 headers, a test pipe (so no cat), and an MBRP CatBack. On the MBRP catback there is almost a 2 foot resonator and there is a mufler. I stiff get an occasional back pop from lack of back pressure. It only happens maybe once a month so I doubt its anything to worry about. Before I put in the test pipe there was no problem with back pressure. So if you are running a straight exhaust (like me) you will probably need close to the same setup as above to keep your back pressure about right.

 

I have a 4-2-1 obx header, with 2 1/2 inch piping from the header all the way to the cherry bomb turbo muffler.

 

I don't think that you are loosing back pressure..... 2.5" is the highest diameter recomended for N/A....

 

I installed a 4-1 header, with a hi flow cat from carsound, a 28 inch glasspack, and an apexi N1 exhaust (not the turbo one) and i feel like i lose some power in the upper RPM range, like after 5700, i thought it was the hyper racing clutch at first, because i installed them around the same time, but the clucth is fine, its definetley the 2 and a half inch tubing on the exhaust, I should have stuck with 2 and a quarter, but they did a good job on the 2.5 inch so nmext year it will bne ready to exhaust 7 to 15 pounds of boost, if ya know what i mean.