Following in the wake of the plug sleeve thread I thought it unfair to jump on someone else's bandwagon.

I am routing my leads under the manifolds. Previously the leads were bunched together near the back of the block (which I understand is a bad thing).. I have bought new Moroso 8mm blue leads and their seperators and will need to 'tie' them away from the headers. Can I use standard electrical ties, or do I need aluminium ones to resist the heat?

Do you think my leads bunched together before could have been the cause of this mystery hesitation above 4000rpm that I have had to live with for a year?

 

2Fast,

You can use the factory wire looms available from GMPP to route the wires behind the heads and under the headers (along the extreme lower edge of the heads). These looms bolt to the ¼-20 holes in the lower edges of the heads and clip the wires along the entire length of the heads.