So, is their any “known” pattern to go with? At this time I have b&b 3” Exhaust with hjs 100 cel cats on the back of my tial a28/60’s. Thinking of going with tial hta 30/76 and wondering what’s the best way to go with the Exhaust? Maybe straight pipes on to the 100 cel cats? Just straight pipes off turbo? Any advice is helpful, thanks.

 

Here is a nice write up from John who has a wealth of knowledge which may help you decide.
https://www.6speedonline.com/forums/...e-settled.html

 

Thanks for that, I’ll enjoy the read

 

I've tried the loud pipes thing and I advise against it because the drone with these cars really resonates in the cabin.

 

Well, I have 100 cel hjs already. Still not sure, when changing up to 3076 if I need to mod Exhaust? I think I may price up some big open pipes and try it. I ride bikes with stupidly loud pipes so have gone a little deaf now

 

It's something with the way the car is shaped with the engine in the back or whatever that has a terrible amplified resonance in the cabin with straight pipes. It ruined the experience for me.

 

Maybe I’ll try straight and if it’s too bad, weld pipes to the cats

 

What size (diameter) are the HJS 100 cell cats you have? The larger the diameter, the greater the flow...

 

Not sure, they are welded to the 3” b&b and have been on the car a while.

 

I have 3" X pipe with no tips on the GT2. TopSpeed must have got it right because she is pretty quiet if NOT on gas. It is very hospitable at highway speed and not much louder in street driving than my 7TT with 3" bbi style mufflers. It's going to be picky but if "right" its not bad, I have no carpet and a cage in the back and the GT2 gears are louder than exhaust at cruise.

 

i dont know much, but what i do know. is running catless with a tune x-pipe exhaust is a 10% bump in usable/noticeable power over same with 200 cel cats.

i'm thinking of removing them again, as i love the smell of fuel in the morning.

 

John showed that with the right cats, you can make the same power as catless, just a high cost to do so.
as for drone, if you add anti drone pipes to an d pipes setup, you will have bas8cally zero drone. I have done this on the system o build and at cruising speeds there is zero drone.

if you can free up your exhaust flow, it's a big plus on a turbo car.

 

So just a pipe to the back is not good

 

Simply measure the diameter of the catalyst and that will tell you what you have. If you have genuine HJS motorsport cats, you will also have an Emitec marking on the catalyst with corresponding part number (HJS does not produce the cores, Emitec does). You will need an HJS 100cell motosport 130mm catalyst to provide ZERO power loss at a 600-650whp level, and a 140-150mm at a 700-750 whp level. Most exhaust manufacturers will use the smaller 100-120mm 100 cell versions which are much more restrictive and good sub 500hp power levels. As I've mentioned a million times, not all 100 cell cats are the same...

 

Yes, not fancying crawling under it at the moment, it’s winter here and currently 2* outside!

i have a picture on an old laptop, I’ll dig that out and see if it sheds any light. Tbo I’m leaning towards a piece of pipe on the back of the turbo