Suppliers for straight pipe exhaust?

for anyone looking to retain boxes as a method of increasing back pressure and thus power I'd like to point out this is a myth.

an engine will produce pulses within the exhaust ports as the valves open/close, these pulses travel along the manifold primaries before merging at the secondaries and again at the final intersection into a single pipe.

a well designed exhaust will have tuned lengths that allow each individual pulse to latch onto the next basically pulling it along (like tow on an F1 car). a badly designed exhaust like the cast manifold on a standard kr will allow the pulses to effectively colide and thus reduce in velocity.

any box with filration extending accross the system (such as cats etc) will hamper the free flow of gas and thus cause a reduction in its velocity. hense you will only tend to find "muffler" style boxes in a good sports exhaust for noise reduction purpouses only.

basicly you want the gas out as quickly and freely as you can, giving it something to fight against i.e. back pressure is counter productive.

discuss....

 

oh and one more thing....

if you want to get rid of another box then make it the one nearest the axel, by the look of it it has a couple of near 90 degree bends (although I need to cut one open to confirm) judging by the entry and exit pipes.

from the last 12 weeks that I've spent playing with a CFD package I can tell you that this will be causing a big reduction in gas velocity as it rounds each bend compared to the rest of the system + its a heavy little blighter!

 

This is a Saab competition exhaust. I had one back in the 1970s. One silencer and not noisey. The standard system only had one silencer, but was smaller diameter, and whisper quiet!

 

I run a Supersprint 2 box system (backbox and over the axle) with a TSR manifold, contemplating removing the over axle box as it sounds a too "farty" at the moment. Nice on tickover but I let the Mrs drive and if you're not planting it then it sounds so farty and feable. I last had a single box system, same car but it was a magnex back box and this was unbearably loud. I'm hoping the supersprint back box will be quieter.

So is the 16v diameter 2" or 2.25"?