Which is better?

I am trying to find out the pro's and con's for each these exhaust systems including the downpipe i have been told by about 10 different exhaust places 3.5 inch system is the way to go if im serious about performance than i ve been told by i think it was 4 other exhaust places that 3inch is the way to go because 3.5 inch runs heaps rich and also tends to back fire. Im wondering obviously the 3.5 system is more expensive right so therefore would they incourage me to buy a 3inch system.

In the car game, you pay for what you get. Cutting corners on things is not always the best idea. If your running a turbo car look at it logically. A turbo forces air through the motor and out. The more exhaust you can flow through the car, the faster it goes. Running a same size exhaust which would be from the turbo all the way back, you will already notice a big gain in power. I would strongly suggest running a bigger exhaust for the turbo, exhaust doesn't make a car run rich, it's the computer that makes it run rich, running a S-AFC will make it a little easier, and not run so rich. If your running a n/a car, it still will help but you most likely won't notice a big difference till later. If you have any other questions, please ask.

In the car game, you pay for what you get. Cutting corners on things is not always the best idea. If your running a turbo car look at it logically. A turbo forces air through the motor and out. The more exhaust you can flow through the car, the faster it goes. Running a same size exhaust which would be from the turbo all the way back, you will already notice a big gain in power. I would strongly suggest running a bigger exhaust for the turbo, exhaust doesn't make a car run rich, it's the computer that makes it run rich, running a S-AFC will make it a little easier, and not run so rich. If your running a n/a car, it still will help but you most likely won't notice a big difference till later. If you have any other questions, please ask.

Thanks for the advice by the way my car is a turbo i recently bought it so am still learning. i logically thought that running rich had nothing to do with the exhuast system like you said but wasnt sure about the back firing, so those exhaust guys have no idea what there on about i take it.
Thanks alot for your help

try the mines ECU VX rom