How big should i make my exhaust piping?, 95 Celica ST Options

[WhipCreamCelica]

I have an invidia n1 exhaust muffler on stock piping, i was planning on going to a muffler shop and getting my catback piping in 2.5", and my down tube for my headers in 2", would these measurements be correct for my 95 st??? thank you, i need to know, i also have stock headers right now,

[Micky_lovescelic...]

I have an invidia n1 exhaust muffler on stock piping, i was planning on going to a muffler shop and getting my catback piping in 2.5", and my down tube for my headers in 2", would these measurements be correct for my 95 st??? thank you, i need to know, i also have stock headers right now,

A number of things play into exhuast design, not simply a diameter. Design efficiency as a complete system is very important, material selection, beyond this there are mechanical and ancilary attributes that contribute to the values that equate the ultimate formula. Again, what is desirible for race car is not pragmatic for road car. The area in which engine speeds
are operated at play a fact.

You have a 1995 ST, so I'll assume you have a 7AFE and not swapped anything. I can tell you that very few firms have dynos deticated behind systems
for the 7AFE. How response and power is created is very important. Remember the factory management is fairly crude, and is not capable of making major adjustments.

I would need more information about what you are trying to achieve to give you a professional opinion. A number of factors and a dollar to power ratio.
Is this merely a replacement, or is this for something special or you have specific areas of interest that need fine tailoring?

Regards,
Mick