Is there really a difference between a 1 5/8" headers or 1 3/4" headers? I have a TPI 305. Any info? Has anyone had the SLP headers, what do you think of them?

 

I have the slp headers, and they are very nice (except for the occasional fit issue)

1 5/8" is supposed to be better for the 305's as they won't push that much air. I put the 1 3/4 on mine thinking I had a 350. I lost some of my bottom end, but IMO most "upgrades" push your power band up a bit. I ended up dropping in an LT1 now...and now I have that header fit issue where the headers rub up against the steering column...I'm not too concerned though, there is now a small air gap and the metal going towards the rack and pinion isn't getting very hot (Thermal dynamics pushes the heat along the exhaust pipe, not across an air gap)

The technical difference is something I do not completly understand yet, but basically you want some backpressure in the system, the bigger headers reduce the backpressure and will cause a loss of some low end power on smaller motors. If you plan on upgrading to a 350 in the future, just get the 1 3/4"s now.

 

<img src="http://www.corvetteforum.cc/zeroimg/smilies/banghead.gif">

 

i like them, whatever headers u chose get them coated.

 

I got the SLP 1 5/8 headers and recommend them. Except for the y-pipe, they fit well. Skip on the install kit though.

 

1 5/8" can support 450hp on a 350 so they are perfect for your 305. I think any 350 making 300+hp should use 1 3/4" but the smaller will suffice.