Hey guys, I'm planning to de-cat and change the exhaust system on my GE8 (Automatic Transmission) I was wondering what is ideal pipe size to go for?

I have K&N SRI installed and Plan to put in an UniQ chip after the exhaust mod.

Some guys told me to go 57mm down pipe then 45mm mid pipe through.

Or should I just go 50mm all the way through?

Help please

oh and I wish I could get those HKS and T1R exhausts, but unfortunately they are too much to bring them in to South Africa. So I have to do it locally.
That's why i'm asking for the ideal pipe size

Thanks!!!

 

don't waste anymore money modding your automatic fit.

 

My question was pipe size, not: is it worth it modding an auto fit :S

Now please someone tell me the ideal cat delete pipe size for the auto Fit

Thanks

 

what would make it any different from a manual transmission fit? just measure the size of the b pipe and make the cat delete pipe the same size?

 

If i want to change the B pipe too? Or shouldn't I change that? Should it stay the same size? Or can i go bigger?

thanks!

 

Does anyone know the pipe size of the T1R Racing Convertor? is it 50 or 57mm?

Thanks!

 

I believe the T1R racing converter is 50mm. From what I've heard, the Weapon-R Cat-delete is supposed to be better, as long as you run a resonator/glasspack and muffler setup.

 

So all the well known brands seems to only build 50.8 pipes for the Honda Fit? I thought the OEM pipes were already 50.8mm. Shouldn't the after market be bigger?

 

The T1R is JUST a cat-delete. That's all it is. And 52mm is the diameter of the Buddy Club Pro Spec exhaust for our cars (IRC). I don't think the factory piping is 50.8.

If I remember correctly, the Weapon-R cat delete "header" for our car takes the 4-1 configuration of the factory exhaust manifold, and changes it to 4-2-1 with a more free-flowing design and no cats. Lyon[Nightroad] has used it and he seems to be a firm believer in using it for N/A applications. According to Weapon-R, it uses a 2.5" to 3" collector, which I'm almost sure would be bigger than a stock collector. It also uses stepped tubing.

I haven't used it myself, but I like the looks of it more than I like the T1R converter. Regardless of the size of the pipe, you'd still have 4-1 piping. That's good for power up top if it flows well, but 4-2-1 is much better for low end torque.

 

Whats wrong with modding a auto? According to my Vin my car is auto and its pretty quick

 

Nothing is wrong with an Automatic transmission. Since most forms of racing use automatics/clutchless manuals now like top fuel drag racing, outlaw drag racing, Formula 1, and all other kinds, an Automatic is just fine. The only real difference between an A/T Fit and a M/T Fit in terms of customization, is the gearing. You can't re-gear an automatic. But that's why companies like Level 10 and TCI exist!

 

By the way, to answer the OP's original post, you should maintain the same diameter of pipe all the way from after the last catalytic converter to the exist. It is also ideal to match the diameters of the exhaust to the cat-pipe/test-pipe. The point is to maintain a constant velocity and avoid any turbulence or loss of velocity.