Performance wise you will never need a 5inch exhaust.. it's still a 4inch Downpipe.

 

You can buy the 4 or 5 inch system and buy the muffler delete pipe at an extra cost. To be honest, do the 4 or 5 inch WITH the muffler, theres not that much difference in sound and the muffler is a flow thru design so it flows. I have 4 inch duals with the muffler and its sounds sweet.

 

thanks for the advice guys. this is killing me! lol! i found another thread where everyone is behind the 5 inch kit! lol! i dont know what to do. i sure as heck dont want to do anything ill regret later. ok, so performance is not an issue, is there really alot of sound difference between the two? and can i get a delete pipe for the 5 inch if i decide to go that route?

 

Clay, i seen on another post you were planning on upgrading to the 5 inch. are you planning on running a muffler or not? and why did you opt for the 5?

thanks!

 

I have the 5" exhaust with no muffler. If I was to do it again I would go with 4" with muffler. The noise without a muffler gets annoying on a long trip, and 4" is cheaper.

My brother worked in a performance shop and dyno tested both 4 and 5" systems and found no difference in performance between the two.

 

Whatever you do, get the bellowed up pipe kit for sure.
The old style donut gasket up pipes are notorious for leaking and that costs in engine performance because you lose drive pressure for making turbo boost.
With the bellowed pipes, the exhaust is completely sealed and all the exhaust must exit through the turbo.

 

I agree with Dan and Andrew on the point of bellowed up pipes, but we have to make sure that it will fit an early 99. I dont think it will?

Clay, can you help the man out?

 

Oh, it's an E99.
It won't fit unless you go to the late turbo and pedastal.

 

I got a pedistal and late model stocker in my shop. I beleive clay has and intake spyder.

 

4" with muffler is plenty performance-wise and sound-wise. I love the sound of mine and minimal drone in the cab. Down side to 5": Cost -- 4" is usually cheaper. Fitment issues sometimes. And no gain over a 4" unless you're going for crazy HP levels (like 600+). If you're looking for an excuse to get the 5", you have a slightly different sound with it, looks, and you can say you have a 5" exhaust on FTE. That's about it.

Here's what my 4" MBRP with muffler sounds like:
<embed width="600" height="361" type="application/x-shockwave-flash" allowFullscreen="true" allowNetworking="all" wmode="transparent" src="http://static.photobucket.com/player.swf?file=http://vid370.photobucket.com/albums/oo148/Izzy351/Fuel%20System/FuelPressureDrop.flv">

 

I will keep the muffler when I upgrade because I like the sound better. I am going to the 5" for the look, there aren't any real performance reasons.

 

If I ever do mine again, I'm spending the jack on a full T304 SS 4". I'm a little disappointed in how the T409 looks after 3 years.

 

Joe, do you have a link to that video? I am having trouble playing it on here for some reason?

 

mbrp 4'' t 304 u will love it