Twin 2 1/2 Inch Exhaust Restricting?

[luvmyxr6t]

hey guys just wandering if a twin 2 1/2 exhaust is not going to restrict my car once it gets into the mid-high 400 rwkw. A lot of the boys have 4 inch exhausts once they reach high power and I was wandering if I need to change my current exhaust to help support that high power. cheers

[bcl]

As a guide don't go over 370rwkw with a twin 2.5", as it becomes restrictive at the point a pipe separation, and more of a bottleneck as power goes over 400.

I use THR exhaust which has 50% 4" front section and tapering to a 3.5" rear section for optimising gas flow and better torque, in conjunction with high flow mufflers.

Brian

[jaymen]

Hi Brain so would this be the same as using a twin 2 1/2 redback Quads? Are they only good for 370kws aswell?

Cheers

[bcl]

Don't get me wrong, you can still push up to 400 with a twin 2.5" and run a 10 sec pass as some guys have done. Even an xforce will suit 95% of people;'s needs.

It's just like a turbo or anything else, where the law of diminishing returns applies.

Assuming the mufflers are OK and flow well, you have to look at the quality of the pipe separation at the split point on the inside.

In theory any bending of pipes and pipe separation causes non optimal gas flow.

Sorry, I have not seen nor had any experience with the Redback system, only heard that it is supposed to be good quality. However, just because an exhaust looks shiny on the outside it does not mean that it is well constructed on the inside.

Brian

[Godzilla]

The Redback system flows well, all mandrel bent, straight through mufflers without baffles whether its the twin 2 1/2inch or quad outlet system however if I was serious about producing some serious power id go single 4 inch with straight through mufflers and a 100cpi high flow cat.

Even on my GTR with a single 3 inch and going to a 4 inch with a high flow cat or even better still with a decat pipe, the top end power difference in really noticeable when running over 400awKw.

Its all about flow from the exhaust to the head to the intake.

[typhoon_freak]

I had a twin 2.5in system and was making 420rwkw, that had a gutted cat and went to quads at the rear, with a 4in dump and mid mount manifold. was a struggle to get there, better of going 3.5in

[Panda Eyes]

I am happy with the quality of my twin 2.5" redback mild steel system. I'll be chasing 450rwkw with it.