i am thinking of going a little more on my exhaust. right now i have just slp lm catback. i am thinking of lt headers. i guess my question is about the cut out. i am trying to get exactly what they are. here is my take, they are before the catalatic converter and allow you to open them when one wants. say at the track and then they can be closed to drive on the road. am i close? also which are better electric or manual?

 

Thats pretty much it. It basically gives the effect of duals without the noise and its street legal (provided the cutouts are closed while on the street). There is less backpressure with cutouts than duals, but if you are making enough power that doesn't matter too much. Also, cutouts are less expensive than duals, but you lose some low end torque.

Manual cutouts require you to get on the ground and open and close them. Some people find that to be a pain. Electric cutouts are expensive and I hear they sometimes leak, but they are a easy to open and close. Thats also nice when you are sitting at a stoplight and someone revs on you and you open the cutouts and watch the expression on their face change. Its up to you on preference and how much money you want to spend.

 

I think the common installation place for the cutout is after the cat(s), just before the intermedate pipe goes over the axle. If you locate the cut-out in front of the cat, you run the risk of getting bad O2 sensor readings on the passenger bank.

 

i also have a quick question relating to this. I have heard running just straight true duals is hard on your engine due to lack of back pressure.

Would running with your cut out open all the time possibly cause damage or be hard on your engine due to not enough back pressure.

 

i drive with an open cutout all the time and know many people that do.i have not heard of or noticed any damage caused by this.. but thats a good question. does anyone know?

 

Ive also heard it shows a small decrease in gas mileage, but Id assume its a myth

 

Doubt it, if anything, one could argue that it would help gas mileage by allowing the engine to breath better. Although,on the other hand, I could see it decreasing gas mileage because you will want to spend alot more time in wide open throttle to hear that lovely sound.

 

With cutouts you do have a lack of back pressure and less low end torque. However, this is compensated by increase hp. When you go to the track and race, you will be at high rpms and the lack of bottom end torque will not be a factor. True duals have slightly more back pressure and as a result people don't typically lose and low end torque. So unless you are doing an auto cross where a good portion of your run is under 30 mph, you won't notice a difference.

As far as less gas mileage, I don't really know about that. I doubt that it would be noticiable if there really is.

 

well would there or is there a difference between my slp lm and a cutout. if the cut out is after the cat then it would be no different then what i have now. but if it is before the cat then it would be a huge difference. i am alos thinking of going tru duals. i may just take it to exhaust pros and have them do it. put cut outs before the cats correct?

 

i should put this in my sig, but i ran a 13.82 1/4 at around 99.8, with what little i have done and on the original tires. i would like to get er down to 13.2. i dont have the time slip right in front of me but i will get it and punch it in my sig later. i plan to buy replica 17 zo6 and get some nitton 555r. not sure yet on the tire but it is one i am looking at. i would like to do lt to cutout to cat to lm resanator to tips on exhaust. i havent taken the screen out of the maf but i heard this helps.

 

since you have a freeflowing exhaust already, and you plan to do LTs, i wouldn't worry much about the cutout.

what i would do is put the LTs in, with a dual cat ypipe and then the LM. you will only be losing a few hp with the highflow cats, not enough to make a difference on the track.

 

If you have electric cutouts, I would close them before you turn your car off, though, especially if they're before the cat. When you turn off your car, some cold air from the outside enters the exhaust. With cutouts, or a really short exhaust, the air can sometimes hit the valves. Because of the difference in temperature of the air, it can be harmful to your valves.

Just my $.02

 

so then i could leave it the way it is. the gains are going to be insignificant. should i look into different gears? i have 3.42 right now but was thinking either 3.73 or 4.11. i have read that 3.73 are for the manual and 4.10 or 4.11 are for autos. i am trying to get into the low 13s.

 

other way around....with the low overdrive gear of the m6 you can still run good highway gas milage with 4.10s, while autos work better with 3.73s.

you will see MUCH more gains from gears than you would from cutouts on your exhaust setup. if you can get traction i would say gears are worth .2sec in the 1/4mi.

tricky part is getting the traction

 

ok so maybe i wont do anymore mods on my z. maybe just trick it out a bit with rims and a nonfunctional r/a hood. but if i were to do some mods lth and gears would be the next step aye. probably get me close to my goal of low 13s. noone ever answered me about installing the lt headers. does the engine need to be removed or lifted? is there a limit of hp and torque that the stock 94z is setup for?