ok having a turbo vehicle, im giong to replace the mufflers and will be adding a magnalfow one or two. question is, i guess this would pertain to all turbo vehicles including mine.

if i change the diameter of the piping and the muffler and take the cat off will this make me have boost creep? or will this have other dramastic changes ?

i want the car to sound nice at idle but have mean sound to it at full throttle. im going to go custom here sence i have the ability to weld and have access to a pipe bender and lift. please let me know. the car is completly stock just cone filter.

i want to increase the diameter in pipe size and just juse a magnaflow muffler and maybe a hight flow cat maybe no cat at all.

i know by letting the engine breath better and getting the exhaust out as fast as possible increases the power band. but i didnt want to take a chance of running more boost and blowing the engine.

 

you will boost higher cuz of the free-flow system....I, for example, boost 10psi all day every day in every gear......I have a 3" turboback......you will need a fuel cut defender though.......

 

does that pertain to all boosted cars?
im doing it to mine as well as a Toyota MR2 that is factory turbocharged. why the fuel cut defender ? why is fuel being cut ? thought that only happens to N/A that were turbocharged due it reading boost.

 

Yes, with the stock wastegate you'll increase boost (potentially dangerous). Increasing the boost through a less restrictive exhaust will improve the power band, potentially dramatically. A FCD is used to prevent the ECU from detecting boost beyond 8.6psi, at which point it will cut fuel to the rear rotor.

 

Port the wastegate and you will not spike.............I assume the same principle applies to any other turbo car.....the less back pressure the faster it will boost and it will have higher psi......but i am not too sure ...

 

if we leave the cat on and keep the same diameter piping just replace the muffler with magnaflow will it be safe ? or will there still be spike?
im not sure if unichip makes chips for us but the mr2 will get a new unichip and i was hoping that would eliminate having to put in a fuel cut defensor. dont wanna port cause we are both trying to keep our cars as much stock as possible except for the exhaust.

thanks again for helping out

 

If you left all of the exhaust the same, but changed the muffler, I'm pretty sure that you would be boost safe. Potentially you might get a slight rise in boost, but it should be within acceptable levels.

You don't want a FCD, but a modified ECU would be okay? There is a chip called Rteck which has a built in FCD feature. Actually it's pretty cheap, about the price of a FCD.

 

i think you SHOULD replace the whole exhaust.....it is very restrictive and you can damage your car if the cats are clogged(or ever get clogged in the future) like I said get an FCD or the Rteck(if you have an S4) and don't worry.....10 psi is still safe....once you start hitting 12+ is when u should port the wastegate or get more fuel mods(pump and/or injectors). 2.5" piping or 3" piping will be ok......and I recommend an aftermarket boost gauge.