Okay my exhaust is rusted out and i was wondering if i could just get a exhaust shop to just make some flanges and bolt on a straight pipe with a bend from my header to my stock mufflers where the rust stops , would my ports stop functioning i have a feeling my car is hesitating from a exhaust leak since i got my injectors checked and regrounded my ECU , how much should i be expecting to pay for this , also would a high flow magnaflow cat be good if i added it into the piping?

 

your car wont hesitate from an exhaust leak.

 

wouldnt that cause the ports to stop working since they work off of backpressure

 

If you have an s4 and the rust is in the right place it would affect it. but non-working 6ports would cause more of a bogging at high rpms than a hesitation.

 

well sometimes it pulls hard then sometimes it doesnt? , feels like they open sometimes is this possible?

 

if they are shut it will bog the high rpms if they stuck open youll lose lower end power ~5-10 hp

yes your 5/6 ports can open some times. what make do u have s4 or s5? as for the straight pipe go for it with no cat if u have a s5 but if u have a s4 u will need to do a lil work to keep your ports working. youll have to go with stock cat or elec port or run them off your air pump to keep them working....

 

i have a S4 , what do you mean bogs at high rpms wouldnt that be the same as hesitating

 

Thread Jack: Anyone here run a road race header straight back to racing beat mufflers (no presilencer)? Is it loud enough that you wish you had a presilencer or intermediate mufflers? Is it loud enough to get attention from the police?

 

Im running on some right now. Its dual road racing headers for S5 RX7s. No cats and straight pipe all the way through until I get my muffleres ordered. Its pretty loud. Sounds like a motor cycle/muscle car (atleast that what people say to me). Im always looking out for cops and I also dont go anywhere. But to work and back.

 

yes and no hesitatation is more of a erratic stumbling. bogging down happens when the engine gets to much air or fuel and takes a while for the engine to catch up.

well since u have a s4. do some research on how to keep your ports working if you wanna run a straight pipe. i wouldnt run a cat. i cant tell ya how much it would cost my guess would be around 200.

 

Ok, so the 6 ports need back pressure on an s4, I get that........ I'm stumbling on how to figure this out, because I have an 87 TII and I wanted to run straights. I know when I was driving my car with only that cat on (by the way which was loud as hell, but f'n fun as hell, and made me parannoyed about the cops!) it was just running just fine. but I know that isn't straight pipes. but how does it not function if it is straight pipes, what exactly happens?

 

i think its because your TII is force fed so i dont think it gets a chance to bog- just a thought.

 

you dont have to worry the t2 does not have 6th ports. on a turbo car you want the most free flowing exhaust you canhave, except if you dont have the right stuff to manage it(fuel/timing) a freeflowing exhaust on the t2 is a risk because of boost creep and a undersized wastegate. As for fredster i have seen some electric 6th ports and there are threads on how to make your own using a walmart air pump. I remember reading that it does not work off of backpressure it might work off vacuum? not really sure but alot of people just end up wiring the ports open when up grading the exhaust. If you wire them open with a large exhaust 3in you will loose alot of low end if you are staying na 2.5 or 2.75 should be decent.

 

I've got a straight pipe and it's pretty loud, especially over 4k rpm's. It seriously sounds like a F1 car. I don't usually rev that high around town, but it is a nusance because of the added volume and the aggressive nature of cops around here. It adds some HP, but not much than say a catback. It mostly adds volume. I say get it if you need to save a buck and get your daily driver going again, but seriously consider a better exhaust alternative like Racing beat etc....

And if you have an 86-88 NA you'll need to wire the secondary ports open since you won't have any back pressure from the pre-cats. I believe 89-91's have electronically actuated ports so you'd be ok.