4urxtc

iTrader: (2)

Would having stock USDM SC300 cat and exhaust cause my 1JZ to not see its full boost under load? I get about 6 psi and then when I get upwards in the rpm range it starts to slow drop. Like its not flowing like it should. I have stock intercooler and stock intake. I also do not run a boost controller of any sort. So its as stock a swap as possible.

Just curious if anyone has a suggestion. Thanks

hovsc400

it really shouldnt but you should start by going through your vacuum lines first you may have a leak somewhere

4urxtc

iTrader: (2)

I am going to try and see what I can find on the vacuum lines and see what i find. I will check for boost leak also. I just dont know what it could be other wise.

FatBrian81

iTrader: (2)

There's one sure way to find out! Unbolt the downpipe from the stock exhaust and let her rip.

4urxtc

iTrader: (2)

haha true.... That would be fun to make some loud noise....

MKIVS374

iTrader: (2)

LOL yup. I have stock JZZ30 full exhaust and yes it will hold you back big time way to much back pressure.

4urxtc

iTrader: (2)

If I am not mistake a stock 1JZ's stock boost is 10psi if I am correct?

hovsc400

how much different is a stock soarer exhaust vs sc300 exhaust...i could see the turbo spooling up slower or taking longer to hit full boost but in my experience low psi has always been connected to vacuum issues my last issue i had when i had a turbo car that kept me from boosting properly was leaks in my intercooler piping fix it and boost went back to normal but that was on a GST...otherwise good luck i know its driving you crazy not getting your proper performance out that jz

4urxtc

iTrader: (2)

It does drive me crazy because I want to experience the full fun of the 1JZ... I am going to go over with tooth and comb... lol