I plan to turbo my GS300 with the same motor. It has 120k miles on it. The reason I am not swapping is because I want to keep the car road legal. I cant get an emission inspection with a JDM ECU or with a standalone so my best bet is to turbo what I already got. I plan to go for 400hp with a tuning a piggy back. I've read on the forums that 400 hp is a safe number with the stock engine however, I want to have more of a safety net. I plan to just change the head studs to ARP head studs. I believe ARP 203-5405 are the correct ones (correct me if I'm wrong). My real question is should I change the head gasket while I'm there? A few people have said to me, if the head gasket isn't leaking or broken, then leave it alone. I'm totally find with just changing the studs without taking the head off but if its advisable for me to change the head gasket also then I will do it.

 

Which turbo unit are you considering?

Are you upgrading the suspension, brakes or tires?

Asking bc I want to rebuild a GS300 along the same lines....Why 400hp?

 

I was planning on using the CX racing turbo kit with the GT35R turbo.

I got 18x10 wheels all around. I also have LS400 front brake calipers. Finally for suspension I have a DSpac front and rear strut bar with a Megan Racing Rear Sway Bar. I would only say the brakes and wheels are necessary just so you can stop when you start going fast.

I read people safely reach 400hp with the stock engine and some tuning at about 12-15psi. So I wanted to be safer with installing main studs to hold the head down but I'm not sure if I should replace the head gasket as well.