Right, been thinking if getting a decent set of aluminium heads for my 89 GTA, thing is, been looking through summits website and on nearly all the heads..... in the application part, its states that they only suit small blocks up to 86!!! wtf Whats going on here? Surely a set of edelbrock rpm or some trickflows would bolt straight on? What gives?

Are you serious? Aftermarket heads have been discussed a million times. YES they have Edelbock & Trickflows that will bolt up. Do a search and/or call Summit.

you dont have to be a jerk, ffs
I KNOW you can get heads!!!!!!

The question was WHY!!!!!!!! they state only up to 86 on all the heads
on summits site!!!!!!

Not all the heads. If you have a stock application (which you didn't specify), then you would want something like this...

Per the Summit site:

Edelbrock 60859
Cylinder Head, Performer, Aluminum, Assembled, 60cc Chamber, 165cc Intake Runner, Chevy, 5.7L, 1987-95

These are centerbolt heads and have the EGR crossover.

the pre/post '86 generally refers to the intake manifold bolt pattern. All of the SBC heads will bolt onto any GEN1 (not LT1/LS1) block. However if you wish to reuse your existing intake manifold you will required a set of heads with the post '86 intake manifold bolt pattern. The center two intake manifold bolts on each side are angled differently. If your thinking of upgrading your intake aswell (i assume your either TPI or TBI right now) to somthing more capable of fully utilizing the potential of performance AL heads then you have free rein to choose whatever heads you like.

-Z

Ah right, so its the intake bolt pattern that changed after 86.
Didnt realise that happened (hence the confusion)
With the TPI systems been around since 85, didnt realise they werent
all compatible with each other.

Yes, the plan is to upgrade to a higher flowing manifold,
hadnt decided if that was hi-flo tpi or a stealth ram,
tho i see now that either will bolt to aftermarket heads.
Makes sense now,

Thanks for clearing that up for me.