Curious for a 95 351w. Factory head since 351, GT40 for bigger exhaust valve, or GT40P

 

Gt40p outflows the Gt40 by about 5% despite smaller exhaust valves, and the chamber design is more efficient. But, that better chamber comes at the cost of the awkward plug angle. Most LT headers can work despite that. However, for a no bs install the Gt40 will be easiest.

The combustion chamber is a little tighter in the Gt40p as well.

 

Just some 90 plugs clear alot up doesnt it?

 

They can help. I only needed 1 90degree boot, on #7. The rest had plenty of clearance. A short plug could be used too. Different headers might not need that stuff at all. Where people run into real trouble is trying use shorty headers that hug the engine, like in a Mustang.

 

Do you have trouble changing spark plugs on either side?

 

Seven of them are easy, but cylinder #7 is difficult. I had to modify a socket. I've heard Flotech headers fit well in that regard. I have some Chinese ss headers, they needed a lot of massaging to fit: tight to #7, hit the starter, and the flange holes were way off.

 

As boarding said, flowtechs and most long tube headers designed for the trucks have plenty of plug clearance with p heads, as the primaries come straight out before beginning their bend down toward the collector. With shorty headers, you'll have to get creative to install and access plugs