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+--- Thread: gt20 exhaust system (/showthread.php?tid=27165)
gt20 exhaust system - Chris_90 - 12-10-2014
So slowly getting my gt20 ready for bolting on I'm doing a 3 inch down pipe with flexible joint, then gonna reduce to 2.5.
What I'm wanting to no will it be ok to reduce again to the standard system size near the back box area? Or will it be to restrictive and best to stay 2.5 all way back?
RE: gt20 exhaust system - Dale - 12-10-2014
(12-10-2014, 08:32 PM)Chris_90 Wrote: So slowly getting my gt20 ready for bolting on I'm doing a 3 inch down pipe with flexible joint, then gonna reduce to 2.5.
What I'm wanting to no will it be ok to reduce again to the standard system size near the back box area? Or will it be to restrictive and best to stay 2.5 all way back?
3 inch down pipe is abit extreme I bet the elbow off the blower isn't much bigger than 65mm! Don't forget if you drop back to std near the backbox not only will you need a train of reducers it will flow no better than a std system it's only as restrictive as the smallest parts!
RE: gt20 exhaust system - spike2002 - 12-10-2014
Just run 3" turbo back will sound mental my mate has got his 3" straight thru and is awesome haha
RE: gt20 exhaust system - Chris_90 - 12-10-2014
(12-10-2014, 09:06 PM)spike2002 Wrote: Just run 3" turbo back will sound mental my mate has got his 3" straight thru and is awesome haha
Not wanting to go for loud, got a baby coming.any min now and I don't finsh work till late so don't wanna be pissing the street off
all tho if I could I would 
RE: gt20 exhaust system - Piggy - 12-10-2014
Run with 2.5 if you can. Iirc 2.25 is standard.
RE: gt20 exhaust system - HDIkyle - 13-10-2014
I run a 3" to tank then reducing to 2.5 i think as i dont want a deep tone. Any videos of a full 3" system compared to a 3" to 2.5" system?
RE: gt20 exhaust system - Chris_90 - 13-10-2014
If I have to i will it's just the cost of 3 inch and 2.5 inch silencers there not cheap. Just gonna take abit more saving then.
RE: gt20 exhaust system - silverzx - 13-10-2014
For a GT20 I'd of thought 2.5 would be plenty big enough?
Just extra hassle to fit 3"?
It certainly won't have any negative effects being 3" though.
RE: gt20 exhaust system - Chris_90 - 13-10-2014
I'd have 3 inch all way though if I can get some decent silencers that reduce the noise level alot.
RE: gt20 exhaust system - Piggy - 13-10-2014
just use 5 cherry bombs and a couple 3" bends
RE: gt20 exhaust system - HDIkyle - 13-10-2014
I think i will go 3" no box's even with no back section its not loud at all
RE: gt20 exhaust system - Chris_90 - 13-10-2014
(13-10-2014, 11:19 AM)HDIkyle Wrote: I think i will go 3" no box's even with no back section its not loud at all
Have to have a listen of it, but ash23's estate with 3 inch down to 2.5 is loud.
(13-10-2014, 11:08 AM)Piggy Wrote: just use 5 cherry bombs and a couple 3" bends
Hmmmmm wonder how much the cherry bombs are
RE: gt20 exhaust system - simonh - 14-10-2014
A bore reduction at the back end of the system isn't nearly as restrictive as at the front end as the exhaust gasses are cooler so far more dense. At the turbo/ hot end of the system the gasses are expanded so need more space to exit the turbo efficiently.
That's why a good elbow and downpipe design even with the standard exhaust bore size will give a noticeable improvement on a turbo car but adding a 3" system to a standard elbow and downpipe will have very little effect.
RE: gt20 exhaust system - Mike - 15-10-2014
(13-10-2014, 11:19 AM)HDIkyle Wrote: I think i will go 3" no box's even with no back section its not loud at all
Kyle.. I've got a 3" turbo back. I can say it is fair loud. To kinda define loud.. People can hear me coming from a fair distance away.