Sam

Im about to put a header on my 7. Do I need a presilencer to go to the cat back ?(the cats have been long removed and in their place a 3' pipe has been placed). I belive there is a presiclencer in the pipe now.

1987RX7guy

iTrader: (3)

Well you need one to tone down the volum of just a straight pipe. You anlso have a S4 car so you need something to actuate your auxilary ports. The Racing bear pre-silencer has a fitting on it to work with the ports and have them function properly.


Santiago

SureShot

I have been there..
The exhaust pulses are WAY louder and sharper from the NA rotary with a header than from turbos or pistons.

If you try a straight pipe to the muflers, you WILL have presilencer back on real soon.

j200pruf

iTrader: (4)

What about using a borla XR-1 sportsman in place of the CAT/presilencer?

1987RX7guy

iTrader: (3)

Well you have to find some other way of opening the ports if you choose that route.


Santiago

silverrotor

iTrader: (1)

What kind of mufflers? Stock? You may be able to develop a tolerance to It. If you have performance Mufflers, look out. A pre-silencer Is going on.

j200pruf

iTrader: (4)

Yeah I will be using a single N1 cat-back, does anyone else make a good pre-silencer other than RB, and does RB pre silencers hurt flow?

bejbis

yes, i would say its nessary.....damnit sam tho, get ahold of me, i live in mobile too.....

Daniel

silverrotor

iTrader: (1)

I have a s.s Brullen Exhaust Pre-silencer. They made mine on site. It will not hurt flow or cause back pressure as much as a (performance) Cat will.

Sam

Thanks for all the info guys, think im gonna get a RB presilencer to go with the header , using that with a pair of bonez mufflers.

1987RX7guy

iTrader: (3)

Nice keep us posted...


Santiago

Sam

oh by the way, im using performance mufflers with removable silencers. If I put those in would there be enough backpressure to open those ports?

rxspeed87

don't see why you wouldn't have enough pressure

if not just put your 6 port system on the air pump
they have writes if you search for it

Project84

By the time the exhaust gets to the mufflers, its past the point where a removable silencer will matter as far as opening the ports. I have the racing beat presilencer. If you look in the inlet side, you will be looking directly into a tube that will vent a small amount of exhaust forward to the split air pipe and operate the aux ports. My presilencer came with a block off plate for the ACV, which is no longer needed. Neither was the air pump needed after that. S5 engine will still need that stuff though.