I am planning on buying an S5 TII within the next week or so, and I am thinking one of the first mods I will do to it is probably an exhaust. Mostly because he already has a 3 inch downpipe he is selling me with it. So I wanted to ask a few questions.

First of all I've heard of free flowing exhausts causing boost creep which could be very dangerous especially on a stock fuel system. so I am most like going to end up porting the waste gate I have already decided that but I am more interested in the fuel system side because I don't really know anything about that.

should I a) just port the waste gate and leave it at that.
b) get a rtek 1.5 and stay with an otherwise stock fuel system
c) get an rtek 1.7 and just upgrade the secondaries to 720
d) do c and anything else I might need(suggestions).

I really want to play it safe and make sure it will run well with predictable boost levels and the fuel system being able to handle whatever boost it might get to after the exhaust frees it up. So I'm not horribly worried about going for the most cost effective solution I'd rather go with the safest one and do everything if I have to rather then doing half and chancing it.

Another question I have is with the exhaust setup itself. I am thinking maybe just straight through with some type of muffler and maybe a resonator because that is the setup I had on my last car (a 2000 Celica GTS) but I don't really know that much about turbo exhausts or rotaries in general so I was wondering what is the best ID for the piping, and also I've seen dual exhausts is there any reasoning to them technically or is it just because they look cool? Any suggestions here would be helpful, sorry for a ton of writing but thanks a lot.

 

Port the wastegate AND upgrade the fuel system. Rtek 1.7, 2x720s & a bigger fuel pump will run about $500, which is much cheaper than an engine rebuild, and will let you put down a lot more power.

Here's a link for info on porting the wastegate: http://fc3spro.com/TECH/HOWTO/KWG/kwg.html. The S5 wastegate is far better than the S4, but there's still room to open it up.

Dual exhaust will have a quieter overall note. This is great if you have a big, catless system that you need to quiet down for the street. Rotary exhaust is LOUD. www.racingbeat.com and www.corksport.com are 2 sites you should visit. I run a Racingbeat downpipe & catback system w/ a Corksport resonator, and it's perfect for street use.

 

Thanks a lot, that's very helpful so by 2x720s you mean just upgrade the secondaries right? I think I might go for a dual exhaust since I want to open it up and probably run with no cats but I also don't want something crazy loud and raspy.

 

Yes, 720cc secondaries.

Duals sound great too, you won't be disappointed.

 

Yes, duals are the way to go. They keep it quiet enough to cruise comfortably but scream when you get on it.

Just wondering, what state do you live in? There's a Utica, MI close to me... wondering if you're local.

 

nah it's Utica NY I probably should have put the NY in there.

 

Ah, thought so.