Where would the best place be to run a boost line from the intake to the gauge ? I really don't wanna drill an extra hole in the firewall.

 

Just use an electronic sender unit instead of running a vacuum hose all the way through the firewall. If you take a look at a company like Autometer, they offer both mechanical and electrical gauges. You can mount the electronic sender on the firewall and keep the hose length to a minimum. I think the extra cost of the electronic gauge is worth it considering there is less risk exposing that much vacuum hose to potential damage down the road.

 

see here: https://www.northamericanmotoring.co...r-dummies.html, posts #1 and #8.

 

If you remove the covers between your firewall and windshield, you should be able to use the OEM harness access holes. Driver side is a nuisance to pull the wiper, but passenger side comes off pretty easy. Have fun ---