hey guys,

so i planning on opening up my 89 GTU n/a fc's exhaust. Not going to crazy with the exhaust cause im saving up for a TurboII swap.

but im getting headers and Hi-flow cat all 2.5 inside diameter piping to my STOCK cat back.... is that possible...if so how can i go from a big diameter to my stock piping.

Also will that mess up the exhaust flow dynamic pattern ; pressure wise?

thanks

 

It's fine. 2.5" pipes will bolt up to stock 2.25" pipes decently.

 

yeah its no big deal. stock catback seems to flow ok too

 

nice! will i need new gaskets ? where can i get them ?

sounds good. thanks.


there wont be any exhuast leak bolting right on from 2.5" to the 2.25" section ?

 

You can get gaskets from the local parts store. Or order them from racing beat or you favorite vendor. Make sure you get the pipes decently aligned, sometimes if you don't get them right they leak a little when doing different sized connections.

 

okay cool. would i need a gasket in between the 2.5" to the 2.25" connection?

so a gasket from the engine block to the headers and from high-flow cat to stock cat back.

 

The 2.5 catalytic converter gasket will accommodate the 2.25 catback.

 

sounds cool.

why does the stock exhaust manifold have so much restriction ?

 

2 flow streams going into the side of a box, mixing, and going out the back of the box is far from optimized for flow. Remember that the exhaust gasses are moving at a pretty high velocity coming out of the port, then they have to bounce around a bunch before finding the exit.