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its factory cat il double check if 2 1/4 or 2.5 inch size
I get what you mean tho.

Stock is 2.25" 400CPI.
Definitely worth looking at.
Unless there are some pinched bends in the exhaust tubing, this will be holding it back, ie the biggest restriction.

Yeah i was hoping to decat it in the next 1-2 weeks. Will let you know how i go.
Rest of system is Mandrell bend. I will have a look through the muffler also when i cut the cat of see what it looks like inside also.

vp304 wrote:...Going to decat it soon as im on stock pulley and reading 11psi at 5500 rpm i think exhaust is holding it back a little.
I know 11 psi sounds crazy high for stock pulley
But the exhaust holding it back would mean higher boost...

That exhaust would have to be really restrictive to be almost doubling the boost pressure.
I would guess that the cat is either blocked or partially melted. Or the muffler has collapsed.

Thats what im hoping has happened so when i decat it will have a look at the muffler then
May unleash a whole lot of power hehehe

Have you noticed any difference in running?

Its always felt from day dot, like it falls over after 4000rpm. Like strong up to 4000rpm then just feels like runs outa puff.
Could be exhaust or could be timing being so low. Or maybe or bit of both.

Those L67's are supposed to be good to 5200 RPM, where they produce their max. power. Max. tq. on those 'early' ones is @ 3200 RPM.
Someone is being short-changed...

Yeah but i was driving a ls v8 before this complete different kettle of fish hehe
I will look into the exhaust tho i think is some funny business going on there

You can do an exhaust back-pressure test. That will verify excessive resistance to exhaust flow. Would save cutting/ re-welding, getting thrown in jail etc.
It would involve tapping in a port fitting before the item you most suspect to be restrictive.