Ive greatly appreciated all the help so far, but I've got a few questions the Y-pipe and free flow cat. First of all, I only have a pop charger on my car so far, but you've got to start from somewhere right? From what I gather the Y-pipe replaces the pipe before the cat, but will there still be benefits for putting in a free flow cat as well? It seems as most people swear by the Y-pipe as a great modification and I'm not about to sway from that. I was looking to get a few mods after the intake and it seemed like the Y-pipe and free flow cat were a good idea, but I was not sure if the Y-pipe would take away from some of the performance benefits of a cat. I would appreciate any feedback.

 

The stock cat isn't very restrictive and you probably don't stand to gain a whole lot by getting a high flow cat. But the y-pipe is definitely the thing to get

 

The y-pipe, by far, was the most noticeable of my mods, the v-force unit was second. The low growl sounds great with the stock exhaust, less the resonator. IMO, I wouldn't waste money on high flow cat. or cat back exhaust system...some 5'th gen max dynoed with and without the stock cat-back system and the only diff. was a whopping 2hp gain and very load noise..

 

I really appreciate the info espically since I will saving money by not getting a mod that hardly puts out any power. I am ready to get the Y-pipe now, but I'll pass on the free flow cat. Thanks.

 

forget the cat! but the catback does make a big difference. i just got my greddy installed and i can feel a big difference on the highend. did you guys know that our b-pipes are smooshed in 2 places which restrict exhaust flow?

 

that in itself makes a very small difference but it is still a bottleneck in the exhaust system. When you install a Y pipe and not do the cat and/or catback section, you are not fully optimizing the flow that the car is capable. You move from a higher flowing area (y pipe) to a lower flowing area - this causes backpressure.

A realworld example would be a 2 liter soda bottle. You have the wider lower portion, then you have the skinny neck where the fluid pours out. If you flip the bottle upside down, the flow is limited due to the size of the opening. Since it cannot flow out at a high rate, you get the bubbles and backflow. Install a wider mouth and more flow is allowed.

 

I dont know if i told anyone but i unbolted my exhaust from the strait pipe back and gained ZERO performance ot speed at the track. Sounded crazy though. I think a y pipe would have really helped me...

 

You kill low end performance when you do that. Shorter exhaust pipes is beneficial for high-revving cars that make their peak power at high engine speeds. It's pointless to do it on a basically stock 3.0L V6