E38 Performance Exhaust question??? NEWBEEEEE....

[lv2exl8]

I am pretty new to the BMW world as I have always been into Japanese cars, but after borrowing my moms E38 740il for couple of months, I fell in love with it!! so now I am going to purchase as clean of a 2001 740i as I can find and as with all my cars performance enhancement is my #1 priority.

Anyhow...... Exhaust will be on top of my list and after doing some research I noticed that I dont have as much chose on E38‘s with out spending a fortune, and most exhaust systems come only as excel back. What about rest of the piping, the resonators, the cat converters??? Can I rip out the resonator and run a straight through piping?? Would constructing thicker custom piping from headers back hurt the vehicle??? And if anyone knows, whats the ideal exhaust piping size to use in order to gain the most torque and hp on this engine???

THANKS FOR ALL YOUR HELP!!!

[Teh Prof]

My E38 has Dinan E39 M5 exhaust headers and catalytic converters, E60 M5 resonator, and Dinan E39 M5 mufflers with the tips modified so that they tuck in under the bumper. It's not cheap to do it that way, but it does sound amazing! Turn up your volume, it's a decent recording...

YouTube - Dyno attempt for my Dinan Stage 3 740i w/ custom built motor

[lv2exl8]

Originally Posted by Teh Prof

My E38 has Dinan E39 M5 exhaust headers and catalytic converters, E60 M5 resonator, and Dinan E39 M5 mufflers with the tips modified so that they tuck in under the bumper. It's not cheap to do it that way, but it does sound amazing! Turn up your volume, it's a decent recording...

YouTube - Dyno attempt for my Dinan Stage 3 740i w/ custom built motor

So in other words M5 headers should bold right on to the E38 exhaust??? I am guessing stock M5 headers would improve performance on a NA e38 engine? Also, if I was to build up my own cat back exhaust, what size piping would you suggest to use on a naturally aspirated E38 motor? And if I was to eliminate the resonators (as I am guessing there are 2 of them), should I expect the check engine light to pop up or not pass emissions? I dought that would be the case, but I thought I would ask just in case.

From everything you have told me so far, I would likely do the following: Use stock M5 headers, custom built my own exhaust using M5 Cat converters, eliminate resonators and use aftermarket mufflers.
What do you think about that?

[Teh Prof]

I actually think that stock M5 headers are definitely not as efficient as they could be. The exhaust headers on my E38 are Dinan headers. You can view them on dinanbmw.com.

I'm thinking 3" piping should be fine for your exhaust.

Deleting resonators will not cause a CEL, but it will make for a drone inside the car. Deleting the cats probably would cause a CEL.