Mike at Turbocharged Innovation just went 11.17 at 129MPH with a crappy 1.88 60ft and 102MPH in the 1/8 in 85 degree weather.

Here is a video of this run.

Car is a 3680lb 99-04 style Mustang with these heads, stock PI cams and intake, stock auto, stock 3.27 rear, aftermarket 3000 stall converter, and his turbo setup.  The rest of the car is amazingly stock.

With a restall of the converter so it can be in boost off the line and some weight savings high 10's at over 130MPH should be realized.  Then I might be able to talk him into some cams finally.........

I have an amazing supply of Romeo cores for dirt cheap for hopefully the next few years that have never had a reject.  I pass that pricing on to you.

Funny thing the flowbench those numbers came from I learned 2 things:

Our exhaust port outflowed every other exhaust port we tested at the same time and a couple were rated at near 200CFM. TFS did the same testing when they designed their new 2V head and their numbers matched mine. You can decide to think what you want on that, it was another shop that did the testing for my posted numbers.

Our intake port will pick up ~20CFM through the low and midrange and ~10CFM up top if you remove the swirl dam like everyone else's head.  However nobody has proved removing the swirl dam actually makes more power unless they also have more than 20lbs of boost.  Removing the swirl dam does lower the swirl dramatically, that is evidenced by the coloration of the pistons on motors not covering the tops of the pistons cleanly anymore.

And finally our numbers are de-speced slightly.  Our heads typically flow 5-10CFM higher when people get them tested and I would prefer it that way rather than getting a phone call that a head doesn't meet spec.  Last person testing found 210/175 from the Stage 2 head on a proper 3.55 bore fixture (some other shops test on a 3.57 or even a 3.70)

With a 4.6 sized engine 210CFM will support approximately ~7500RPM naturally aspirated before more CFM even needs to be considered according to the established "calculators".  You need a real intake manifold to achieve this as well as the stock plastic intake manifold won't allow much over 200CFM and 7000RPM anyways.

28 inches and stock bore diameter of 3.55"  Larger bore diameters will flow slightly higher numbers.  Some of the other heads out there are flowed at the stock diameter and some at larger diameters, be sure to check when comparing.

Quite simply that is not where the restrictions are!  The restriction on the intake is in the middle of the port and the exhaust is in the bowl and the roof by the guide. 

Chamber shrouding primarily from the slightly larger valves.  These are small bore engines with small compact combustion chambers.  Once the valve moves far enough away from the seat the larger valve itself finally becomes less of a restriction rather than a greater restriction.  The flow charts are also done with a stock bore diameter, a larger bore diameter will favor the larger valves.

Powdered metal works good for valve seat material, and it works decent enough for valve guides.  However all it takes is one PTV issue and that powdered guide fractures easily.  Then it becomes a tiny fragmentary grenade inside your motor.  I have seen enough motors damaged from cracked and fragmented powdered guides to where I don't use them.  Bronze guides also absorb heat from the valve better and transfer to the aluminum head casting better.  Bronze is a much better conductor of heat than powdered metal.

We just got back one of the first sets of heads I had ever done.  It survived 30,000 miles of abuse via 20-25lbs of turbo boost.  The guides had increased clearance by 0.002"  Since we install the guides at such a tighter spec than OEM, these heads came back still within OEM specs (but at the high end)  The stock powdered guides that I have removed are usually 0.010" larger under similiar conditions.

It is done on a CBN Rottler.  You need a super smooth finish for the MLS gaskets and many shops do not have the correct equipment for this.

PI heads get 4 angles on the intake and 3 angles on the exhaust.  We will do different things to the valve job if the application is a high boost blower or turbo.  All valve jobs are not the same, there is much more to it than just the number of angles.

$150 once they arrive to me.  I will send your cores back to you ported.  I do not swap them for another set unless you desire that (like Romeo and Windsor exchanges - we are always looking for good Windsor cores)

Never touched a set so I would not be the best person to work yours over.   Since they are discontinued now is probably not the best time to starting learning them either.

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