By getting the piping bent and installed Tuesday, I finally finished my exhaust system for my 1995 240sx:

Obx 4-2-1 Header
Resonator test-pipe
2.5" exhaust piping from resonator --> flowmaster muffler.


It sounds great; really deep and grumbly if a bit loud. (okay, more than a bit), but now having driven it for a day, I've discovered a noticeable loss of low-end torque. My manager (I work at pep boys) says it's too open, and the loss of backpressure has hurt the engine's rev speed at low RPMs.

What might a cost-effective solution to this be? I really don't want to have to replace the exhaust I just invested in. :\

Would getting a stock catalytic converter and swapping that in for the resonator be a good compromise between high-flow power and enough backpressure for low end torque?

A J30 LSD is in the mail, and once that gets installed the next step is to put on a lightweight underdrive pulley and get it tuned (as soon as I find some cheap fuel management). Would it be better just to wait and deal with this low end power loss via the tune? Is that even feasible?


Also, I have a small exhaust leak at the manifold mount: when putting in the header I snapped the frontmost stud of those holding on the exhaust manifold to the engine, and cracked the EGR tube. I sealed and wrapped the EGR tube, but couldn't do much about the front of the manifold. I asked the exhaust shop who bent and fitted the 2.5" piping to check it out for me, but apparently they didn't do anything about it (despite charging me :[). I know I need to get this taken care of. Do I need to get the stud drilled and replaced? Can I just use gasketmaterial to fill the edges around the front of the manifold? Could this be a large contributor to the loss of torque?


I apologize for the litany of questions, but any and all help is appreciated!

I'm too in love with my 240 to slow down my tinkering, haha.

 

yea it might be that its too open, and the stock cat might help, thats weird tho, i have a 3 inch with a resonator and stock headers and it feels a lot better.

 

get a high flow cat at least for a little backpressure to regain some low end

 

Turbo. Yum.

 

Put the Cat back in it...

You only gain about 1-2 hp by removing the Cat anyway, and you lose bottom end... I'll take Torque over HP for street use any day...