Quick poll - singe or twin?

[m1tch]

Hey guys, Just been thinking about this a lot for my RX7, I will be going for a 4" system...so....Would it be best to have a single pipe and mod the rear bumper to remove the indent for the other pipe? Should I keep it twin? I was just wondering as lots of systems go from 3" to the Y piece, which goes to a smaller diameter, which might be restrictive.

I was thinking if just having a single pipe would be easier (and cheaper) for the power? I do love my twin pipes, but I don\'t know if they are going to be ok for the 400bhp I am aiming for. Also I don\'t know how much a twin 4" system will cost!

I won\'t be going this mad with a single exhaust though:



Or this...

[dthebuk]

single exit will be cheaper right?

[m1tch]

Yeah I am guessing it will be lol, I will have to go custom though, cause all the off the shelf exhausts are only 3". Im guessing if I go to the 4" system the exhaust note will be lower?

[Prof]

Twin exit - FC looks better balanced

[dthebuk]

does the pipe splitting in two cause any kind of turbulence or back pressure?

[TiddlesRX7]

Mine\'s a twin exit and I\'m sure its 4". maybe 3 1/2 or 3 3/4 out of the turbo to the Y piece. It was about £800 but that was ages ago (previous owner ago). Can\'t remember the make but it\'s Korean

[richrx]

i voted twin, they look much better imho:driving


richard

[m1tch]

I will have to have a look around as it looks like I will have to go custom as the systems you buy normally are for the stock turbo location, the new turbo will be different unless anyone has found an off the shelf catback 4" twin system?

[HOSS]

twin on an FC for sure:3gears-rh

[m1tch]

Ok, here is a question, 3" system or 4"? furthermore, if I go custom, how am I going to be able to get down there as I will need to fit the new turbo and new manifold for them to get the custom downpipe made, so would I need to fit the new turbo when I am down at the exhaust shop?

[L18M]

do most aftermarket turbo in similar position? if so then get someone who has got one fitted n get them to measure for u?
do u really need 4"?
IF i get mine done b4 u then can giv u measurements..

[pdtaylor18]

My Racing Beat is a 3 1/2 inch throughout and drops down to a bit less for the rear boxes, thats a twin system. I think there is nothing worse than a rear bumper with cutouts for two exhausts and only one fitted. It always looks as if there is something missing.  You can pick up the entire stainless twin system for about £400 if you are lucky with customs.  I am selling a single large bore system thats will be £400 delivered to your door, Tannabe and OBX so its in this country and ready to fit. The guy will not wait though as he has a buyer for it this friday. Well down pipe anyway.
I voted twins all the way.

[pdtaylor18]

Just to try and convince to go twins, think also that as long as the exhaust is well made, the Y section is the correct length then you will not loose BHP because of it. it will also quieten it down a bit as well so you can do away with a centre box.

[m1tch]

Pete, your system is exactly what im looking for, im still wondering how I am going to be able 2 get there and swap the turbos over so that the downpipe is correct, unless I get the system done in 2 sections, ie catback first which is flanged onto the current midbox and keep the stock downpipe and midbox, then get a downpipe made and a custom midbox to make up the gap? Im still wondering how I am able to get the car to a custom place with the new turbo fitted.

[Prof]

I don\'t think you\'ll need 4" unless your going for over 500 BHP !
 
3" all the way to the back (so 2 x 2.5" is still good for twin exit) will be more than enough as long as your exhaust is free flowing (proper mandrel bent jobby and good back boxes filled with decent wool wadding - not some cheapo loft insulation that will blow out or clog in a hearbeat).